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CONTINENTAL Trace Fossils SEPM Short Course Notes No. 51

by: Stephen T. Hasiotis University of Kansas, Department of Geology, 1475 Jayhawk Blvd. 120 Lindley Hall, Lawrence, Kansas 66045-7613, U.S.A. e-mail: [email protected]

With Contributions from: J.C. Van Wagoner, T.M. Demko, R.W. Wellner, C.R. Jones, R.E. Hill, G.G. McCrimmon, H.R. Feldman, P.A. Drzewiecki, P. Patterson, A.D. Donovan, and J.K. Geslin

Note for this printing: This third printing of SEPM Short Course Notes No. 51 has been altered slightly from the first two printings. A few minor corrections have been made and a figure, misplaced in the previous printing, has been repositioned. Also, the quality of the text reproduction below the color figures in Part 2 has been improved. This printing of SEPM Short Course Notes No. 51 has been assigned the new ISBN Number that is listed below. ISBN 1-56576-124-3

SEPM Short Course Notes No. 51 Table of Contents

PART I: CONTINENTAL ICHNOLOGY: TERRESTRIAL AND FRESHWATER TRACE FOSSILS FOR ENVIRONMENTAL INTERPRETATIONS Abstract .......................................................................................................... 1 Introduction ..................................................................................................... 3 Acknowledgments .......................................................................................... 4 Ichnologic Principles and Continental Ichnology ............................................ 5 Controls on Organism Behavior and Burrow Morphologies ........................... 8 Terrestrial and Freshwater Organism Distribution .......................................... 10 Ichnologic Framework of Continental Environments ...................................... 23 Alluvial Environments ................................................................................ 24 Lacustrine Environments .......................................................................... 30 Eolian Environments ................................................................................. 35 Summary ........................................................................................................ 40 References ..................................................................................................... 42

PART II: OUTCROP AND CORE ATLAS PHOTOGLOSSARY Introduction ..................................................................................................... Trace Fossil Abbreviations ............................................................................. Adhesive meniscate burrows ......................................................................... Annelid trails ................................................................................................... Ant nests ........................................................................................................ Bee cells and nests – Celliforma .................................................................... Beetle traces .................................................................................................. Vertical and horizontal burrows – cf. Planolites, Ancorichnus, and more.. Traces in wood substrates – Paleoscolytus, Paleobuprestis .................... Dung beetle traces – Coprinisphaera, Scaphichnium ............................... Scoyenia ................................................................................................... Steinichnus ............................................................................................... Brackish water trace fossil indicators ............................................................. Caddisflies cocoons – Tektonargus ................................................................ Crayfish burrows – Camborygma ................................................................... Dinoturbation, tracks and trackways .............................................................. Dipteran cases and cocoons .......................................................................... Earthworm traces – Edaphichnium ................................................................ Flying traces ................................................................................................... Freshwater clam traces .................................................................................. Horseshoe crab traces – Kouphichnium ........................................................ Insect larvae burrows – Fuersichnus .............................................................. Root traces .....................................................................................................

57 58 59 61 64 68 71 71 77 79 81 83 85 87 89 92 94 96 99 101 104 106 108

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Snail traces – Scolicia .................................................................................... Spider traces – Maconopsis ........................................................................... Termite nests – cf. Termitichnus ..................................................................... U-shaped burrows – cf. Arenicolites ............................................................... Vertebrate burrows and nests ........................................................................ Vertebrate tracks and trackways – Assorted .................................................. Wasp nests and cocoons ............................................................................... Trace Fossil Summary Sheets .......................................................................

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111 113 115 120 122 126 128 131

CONTINENTAL ICHNOLOGY: USING TERRESTRIAL AND FRESHWATER TRACE FOSSILS FOR ENVIRONMENTAL AND CLIMATIC INTERPRETATIONS By Stephen T. Hasiotis* With Contributions from: J.C. Van Wagoner, T.M. Demko, R.W. Wellner, C.R. Jones, R.E. Hill, G.G. McCrimmon, H.R. Feldman, P.A. Drzewiecki, P. Patterson, A.D. Donovan, and J.K. Geslin

ABSTRACT The type, distribution, and tiering of continental trace fossils (ichnofossils) are useful tools for deciphering continental environments in both outcrop and core. This atlas presents the latest ichnological concepts and provides a comprehensive photocatalogue of nearly the entire suite of major terrestrial and freshwater trace fossils that geoscientists will encounter. The atlas is separated into two sections: 1) concepts and fundamental principles that explain how terrestrial and freshwater trace fossil behavior is interpreted and used to define environments of deposition; and 2) a photocatalogue of outcrop and core examples of continental trace fossils with explanations and idealized line drawings. Section one formulates fundamental concepts of continental ichnology by examining the life cycle of organisms in modern depositional systems. It discusses some of the shortcomings in the current philosophy of ichnology and elaborates on the differences between continental and marine organisms and resultant differences in their traces. The report illustrates how the controls on behavior and distribution of continental organisms can be applied to define continental environments. An ichnological framework for continental systems is presented that is based on analogy to specific environmental controls operating in modern terrestrial and freshwater environments. The framework uses examples of modern and ancient trace fossils to

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define specific environments. Alluvial, lacustrine, eolian, and transitional depositional settings form potential ichnofacies, which are defined in detail by their ichnologic composition. Section two is a photocatalogue of outcrop and core examples of continental trace fossils. Each type of trace fossil is presented with a description, interpretation of the architecture and surficial burrow morphologies, geologic range, trophic classification, and environmental and climatic settings. The trace fossils are illustrated with idealized line drawings as seen in outcrop and in core. Color photographs are used to show the trace fossils as hand specimens, in outcrop, and core from different geologic formations and ages. Many of the continental traces occur in paleosols where the color differences between the trace fossils and surrounding matrix accentuate the trace fossil’s morphology. The combination of text, line drawings, photographs, and figure explanations allows the user to determine what the trace fossil he or she is working with as well as what the paleoenvironmental and paleoclimatic settings were of the accompanying strata. The last two pages in Section 2 (pages 131–132) are summary sheets of the trace fossil and contain representative color photographs and line drawings of each trace fossil in the photoglossary. It is organized by the orientation of trace fossils in outcrop (or core), and the morphologic complexity of the traces. The summary sheets can also be referred to by the user to key a trace fossil morphology into a particular section in the photoglossary. These sheets also include a list of abbreviations of continental trace fossils to be used when measuring sections in the field or describing core at an offsite location. A separate, laminated reference sheet of these two pages is available from SEPM (Product 55004). The laminated reference sheet allows you to have your guide to continental trace fossils readily available wherever you go.

*Address: University of Kansas, Department of Geology, 1475 Jayhawk Blvd., 120 Lindley Hall, Lawrence, KS 66045-7613; [email protected]

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INTRODUCTION Continental depositional environments contain a vast array of life in terrestrial and freshwater ecosystems, but continental ichnology has been given light treatment in books and theme volumes on ichnology (e.g., Imbrie and Newell, 1964; Crimes and Harper, 1970, 1977; Frey, 1975; Basan, 1978; Ekdale et al., 1984; Miller et al., 1984; Curran, 1985; Bromley, 1990; Ekdale and Pollard, 1991). Continental traces are commonly regarded as rare; however, ichnofossils are well-represented in many continental rocks including those associated with coal, oil, oil shale, aquifers, and other economic resources. Modern traces of invertebrates, vertebrates, and plants are common throughout the continental realm, and they are sensitive environmental indicators. Likewise, their ancient counterparts as trace fossils can be used to interpret depositional history, salinity gradients, soil moisture-water table levels and fluctuations, paleoecologic structure, and paleoclimate in alluvial, palustrine, lacustrine, and eolian deposits. This section develops principles for describing and interpreting continental ichna (trace fossils and burrowing organisms) and creates a working framework for continental ichnology (Hasiotis, 1997a). Using examples from modern and ancient continental settings where organism trace-making occur, the major factors controlling organism behavior and distribution in continental systems form the basis for defining continental environmental gradients (explained in detail later). This approach is markedly different from previous discussions in which trace fossils are described from previously interpreted continental environments or facies, such as eolian traces, or floodplain traces. In the present study, environmental factors controlling the organism’s behavior are interpreted from the traces themselves, and the depositional environment interpretation is thus substantiated by the traces. These factors are also independently substantiated by the characteristics of the paleosols that has modified the sediments, as well as from the primary and other secondary sedimentary structures associated

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with the trace fossil. Finally, examples of burrowing behavior are used to subdivide continental environments into ecologically sensitive subenvironments (i.e., subfacies) based on physical sedimentary and pedogenic structures and modern burrowing organisms. The terminology used in this report follows generally accepted sedimentologic usage (e.g., Reading, 1986). The term continental is emphasized in this ichnology study to replace “non-marine” because it differentiates between marine and continental depositional environments containing both terrestrial and freshwater-aquatic burrowing organisms (e.g., Hasiotis and Bown, 1992; Hasiotis, 1997a, 1998a). Other common terms are too restricted in meaning: “nonmarine” delineates a marine point of reference; “terrestrial” is also often inadequate because it is restricted to only land above the water, or on Earth. “Freshwater” denotes life in water that has a salinity of 0-5 ppt, which includes rivers and most lakes.

ACKNOWLEDGMENTS I am indebted to a great number of colleagues who have contributed to this study through field work, discussions, locality information, and the use of personal slides and trace fossil specimens: P. Birkeland (Univ. Colorado, Boulder-Emeritus), T. M. Bown (USGS-retired), K. Bohacs (ExxonMobil), T. M. Demko (Univ. Minnesota, Duluth), R. F. Dubiel (USGS), G. Engelmann (Univ. Nebraska, Omaha), E. Evanoff (Univ. Colorado Museum, Boulder), D. Eicher (Univ. Colorado, Boulder-Emeritus), J. A. Fagerstrom (Univ. Colorado, Boulder-Emeritus), J. Genise (CONICET), R. Goldstein (Univ. Kansas), E. Kauffman (Indiana Univ.-Emeritus), R. Kaesler (Univ. Kansas), J. Kirkland (Utah State Paleontologist), M. Kraus (Univ. Colorado, Boulder), E. Kvale (Indiana Geological Survey), C. E. Mitchell (Univ. Buffalo), J. Morrow (Univ. Northern Colorado), P. Murphey (Univ. Colorado, Boulder), F. Peterson (USGS-retired), A. Sprague (ExxonMobil), M. Sullivan (California State Univ. Chico), P. Robinson (Univ. Colorado

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Museum, Boulder), and C. Turner (USGS). I am especially grateful to the ExxonMobil Corporation for funding my post-doctoral fellowship at the ExxonMobil Upstream Research Company in Houston, Texas. I also thank the personnel and volunteers at Arches National Park (Utah), Colorado National Monument (Colorado), Dinosaur National Monument (UtahColorado), and Petrified Forest National Park (Arizona) for their support and assistance while doing research in their parks and monuments. The manuscript benefited from reviews by K. Bohacs, R. Dubiel, and A. Rindsberg. My most sincere thanks to Carol, Christina, Stephanie, and Snowflake for letting me pursue my research. Lastly, I thank Howard Harper and Kris Farnsworth for their diligence in helping me bring this study to SEPM’s Short Course and Notes series.

ICHNOLOGIC PRINCIPLES AND CONTINENTAL ICHNOLOGY The principles and working framework of continental ichnology have never been adequately defined, although many workers have touched on the environmental factors affecting the behavior and distribution of burrowing organisms and trace fossils (Fig. 1). This section examines the current philosophy of ichnology and the evolution and distribution of modern continental organisms. The principles and ichnologic examples used in this section provide a new framework that unifies the study of continental ichnofossils (Hasiotis, 1997a). These include the physiological limits of organisms and their behavior, the physicochemical factors that operate in continental settings, and the relationship between soil biota and the groundwater profile that play a role in controlling ecological tiering in terrestrial and freshwater environments.

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Figure 1. Current Seilacherian Ichnofacies Scheme showing the relationship between marine and continental environments. Modified from Seilacher (1967).

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Current Philosophy Many workers argue that a continuous spectrum of physical, chemical, and biological processes exists between continental and marine settings (e.g., Bromley and Asgaard, 1991). Others regard continental traces as synonymous with marine ichnotaxa form-genera because they are grossly similar to previously described marine traces (i.e., Bromley and Asgaard, 1979; Fursich and Mayr, 1981; Frey and Pemberton, 1987; Bromley, 1990). The result is that many continental and marine ichnofossils currently share the same ichnotaxonomic designation despite subtle, but significant morphologic differences. Another problem is that many continental ichnofossils have only been identified alongside vertebrate footprints, coprolites, tooth marks on bones, and plant traces (e.g., Hasiotis, 1997a). The majority of terrestrial and freshwater invertebrate traces have not been described in detail prior to this study. Often, when they have been described, the traces were identified simply by general ichnotaxonomic designations (e.g., Gierlowski-Kordesch, 1991; Buatois and Mángano, 1995), or as “worm burrows” or “insect tracks and trails”. This loose identification fails to recognize the details of each trace, and in addition, fails to relate the environmental significance available from the traces.

Evolution and Convergence in Morphology Continental and marine trace-making communities (ichnocoenoses) represent distinctly different life strategies that have evolved separately for nearly 400 million years (e.g., Retallack and Feakes, 1987; Gray and Shear, 1992; Hasiotis, 1997a). As a result, they have evolved vastly different ecological pathways and behavioral-genetic responses. Since they have different evolutionary pathways, organisms in continental versus marine environments differ not only phylogenetically, but also physiologically and ecophenotypically. Similar burrow

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morphologies may have developed in continental and marine trace fossil communities because of convergence in the evolution of body plans, burrowing mechanisms, and behavior (Hasiotis, 1997a). Close scrutiny of the somewhat similar burrow morphologies, however, shows subtle, but distinct differences in morphology. For example, in the case of the similar arthropod trackways Cruziana and Isopodichnus, marine trilobites constructed Cruziana, and freshwater notostrachans and isopods constructed Isopodichnus. Each trace has its own size range and morphology, but they appear similar because both are crawling trails produced by organisms with bilateral symmetry and bilobate structure (e.g., Hantzschel, 1975). Because of the morphologic convergence of these traces, some workers have synonymized the latter with the former (i.e., Bromley and Asgaard, 1979). It can be argued, however, that each ichnologic name should be valid because the traces were formed by distinctly different organisms using similar but distinct locomotion (i.e., number of appendages, uniramous appendages in isopods vs. biramous appendages of trilobites, motion) in distinctly different realms (marine and continental) in distinct depositional environments with distinct behavioral responses. Most importantly, they have different morphologies in terms of size, shape, and structure. Other examples for these subtle types of distinctions will be presented throughout this study.

CONTROLS ON ORGANISM BEHAVIOR AND BURROW MORPHOLOGIES Most marine trace fossils are produced by benthic organisms that interact with the ocean substrate. Marine organisms operate at or below the seawater-substrate interface and as landward as the seawater-sediment-air interface of the transitional zone. Marine organisms burrow into the seafloor substrate for: (1) protection and concealment, (2) respiration, (3) suspension, detritus, or deposit feeding, (4) gardening, (5) predation, (6) reproduction, or (7) as a result of trauma (Bromley, 1990). Each behavior is developed in littoral through abyssal

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environments, with burrow morphologies unique to the depositional and ecological processes (i.e., Ekdale et al., 1984). Even in environments with such harsh salinity fluctuations and energy levels (e.g., brackish water settings) as tidal channels, inlets, lagoons, and estuaries, marine benthic organisms always remain in water-saturated sediment (Pemberton et al., 1992). On the other hand, continental organisms function primarily in a nitrogen-dominated atmosphere, living above, at, or below the freshwater-air or air-substrate interface (Hasiotis, 1997a). Continental organisms live in a variety of dry to variably moist substrates and freshwater to hypersaline aquatic environments, to which they are adapted and into which they burrow for all of the same reasons as marine organisms. Specific behavioral responses (i.e., mating, nesting, food gathering, dwelling; 1-7 listed above) of these organisms is controlled primarily by fluctuations in water table, soil moisture levels, water clarity and salinity, oxygen richness, depositional energy events, and climatic conditions (wind, temperature, precipitation, and seasonality) (Hasiotis, 1997a). In some areas water is unavailable, and moisture requirements are accommodated through diet. Thus, continental environments exert specific environmental conditions with physical, chemical, and biological parameters that determine which organisms can and cannot live there (e.g., Bown, 1982; Bown and Kraus, 1983; Hasiotis and Mitchell, 1989, 1993; Hasiotis et al., 1993b). Where continental and marine realms meet — termed the transitional zone — the environmental controls of the dominant depositional system determine which organisms will thrive and leave the dominant ichnologic record (Hasiotis, 1997a). The transitional zone also includes brackish-water environments generated by the mixing of freshwater and seawater in estuarine environments (e.g., Pemberton and Wightman, 1987; Pemberton, 1992).

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TERRESTRIAL AND FRESHWATER ORGANISM DISTRIBUTION Modern continental biota are distributed vertically and laterally in a depositional environment according to their physiological needs for or tolerance of water, soil moisture, salinity, and their ecological associations with other organisms (Hasiotis and Bown, 1992). Terrestrial and freshwater organisms have different requirements for water or soil moisture, substrate consistency at the water-sediment interface, and the degree and species of ionic concentration and salinity within the water or substrate. Continental organisms may be terrestrial in habitat (above and below the soil, but above the water table; Fig. 2), amphibious (restricted to shorelines), freshwater-aquatic (e.g., rivers, lakes), saline-aquatic, hypersalineaquatic (e.g., playa lakes), or alkaline-aquatic lakes (e.g., lakes in highly evaporative settings). Invertebrates exist in an overwhelming diversity and abundance in a wide spectrum of environments. They are the most sensitive indicators of environmental conditions because invertebrates need to avoid desiccation, overheating, too much or too little moisture, too much carbon dioxide, too little oxygen, or other physiologically limiting factors. Thus, invertebrates have the greatest paleoecologic value in continental ichnology. Invertebrates inhabiting terrestrial and aquatic settings include some of the most diverse and populous classes in the Animal Kingdom (see tables in Chamberlain, 1975; Ratcliffe and Fagerstrom, 1980; Hasiotis and Bown, 1992). Invertebrate traces form a basis for vertical and lateral ecological nichepartitioning (e.g., tiering) of depositional environments because of their dependence on specific soil moisture and water table levels, and because of the sheer biomass of insects with their burrowing larvae instars, pupae, juvenile, and adult stages (holometabolous or complete metamorphosis life cycle). The strong dependency of insects and crustaceans on particular environments is what allows their traces to be used as invaluable tools in studies of continental

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Figure 2. Terrestrial habitat: inputs, outputs, and substrates. From Hasiotis (1997a).

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sedimentology and paleoecology in deposits as old as the Permian (e.g., White, 1929), and possibly as far back as the Ordovician (Retallack and Feakes, 1987; Hasiotis, 1997a). Invertebrates and their traces are useful in delineating hydrologic profiles and ecological partitions (Hasiotis and Bown, 1992; Hasiotis, 1997a; Hasiotis, 2000). Burrowing invertebrates include: (1) insects and arachnids, such as ants (Formicidae), termites (Isoptera), bees and wasps (Hymenoptera: Aculeata), crickets (Orthoptera), earwigs (Neuroptera), spiders (Arachnida), caddisflies (Trichoptera), flies (Diptera) of various types, terrestrial and waterloving beetles (Coleoptera); (2) soft-bodied worms such as terrestrial and aquatic earthworms (Oligochaeta), leeches (Annelida), nematodes (Nematoda); (3) mollusks such as terrestrial and aquatic gastropods, mussels; and (4) terrestrial and aquatic crustacea such as crayfish, shrimp, and crabs (Decapoda), sow bugs (Isopoda), scorpions (Scorpionida), ostracodes (Ostracoda), and amphipods (Amphipoda) (Chamberlain, 1975; Ratcliffe and Fagerstrom, 1980; Hasiotis and Bown, 1992). By far, the majority of invertebrates are insects: termites (Isoptera), sawflies, bees, wasps, and ants (Hymenoptera), and beetles (Coleoptera), of which the Isoptera and the Hymenoptera construct the most elaborate and distinctive structures of all continental (and other) trace-making organisms. Vertebrates (e.g., Voorhies, 1975; Martin and Bennet, 1977; Hasiotis and Wellner, 1999) and plants (Klappa, 1980; Wing et al., 1995) are also useful in delineating continental environmental conditions, especially when used in conjunction with invertebrate trace fossils. Vertebrates and their traces have been of popular interest because of dinosaur trackways and the ichnologic experiments with modern reptiles and birds (e.g., Hitchcock, 1858; Sarjeant, 1983; Gillette and Lockley, 1989; Lockley, 1991; Lockley and Hunt, 1995). They are limited, however, in scope and utility as specific environmental and ecological indicators because vertebrates as a whole are not sensitive indicators of environment due to their large size,

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mobility, and terrestrial habit. Their tracks cross environments with different physicochemical characteristics. Also, little is known about the physiological details in dinosaur trace-making or other behavior. Plant roots, on the other hand, are often not plant specific, and their use for environmental interpretations is not as broad as invertebrate traces. Plant traces, however, are ichnologically useful because many terrestrial and aquatic invertebrates are associated with them for shelter, food, and burrowing pathways.

Vertical Distribution: Invertebrates and their traces Continental burrowers, both modern and ancient, are separated into three distinct groups: (1) organisms living above the water table; (2) organisms living in soils with different seasonal amounts of moisture; and (3) organisms living at or below the water table (Hasiotis and Bown, 1992). Organisms and their traces are distributed throughout the upper, intermediate, and lower vadose zones, capillary fringe, and phreatic zone of the groundwater profile, from low to 100% soil moisture (Fig. 3; Hasiotis, 1997a). The phreatic zone (water table) is defined where there is standing water at the surface or where the pore spaces of sediment are filled with water. In neo- and paleoichnology, the water table and associated soil moisture levels are the primary datums determining the vertical and lateral distribution of trace fossils in an environment. Some invertebrates are restricted to life below the water table, such as some species of oligochaete worms and water beetles, ostracodes, mollusks, shrimps, leeches, conchostracans, aquatic-dwelling crayfish, and crabs (Hasiotis, 1997a). These organisms must live in saturated conditions because of their subaqueous respiration requirements. Others live at the air-water table interface—for example, mole crickets, mud-loving beetles, terrestrial-dwelling crayfish, crabs, and others insects. These organisms have adapted to this environment by respiratory

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Hygrophilic

Unconsolidated sediment

Phreatic Zone

Water in fractures and pores of bedrock; also in chemical combination with rock

Figure 3. Vertical distribution of groundwater soil profile. From Driscoll (1986).

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organ adaptations (e.g., development of gills and gill filaments)—structures that need to remain moist to allow removal of oxygen at the air-water interface. Organisms living above the water table include most of the insects, microarthropods, and earthworms and other annelids. These organisms need low moisture levels for bodily functions and they live in the upper (soil water zone) and intermediate vadose zones of the soil profile (Hasiotis, 1997a; 2000).

Organisms and the Upper Vadose Zone Both solitary and social insects construct many types of burrows and nests that are found in well-drained sediments (e.g., those with relatively deep water tables). Termites (Insecta: Isoptera) are the most architecturally-organized of the social insects. They construct elaborate nests of variable architectures that may be composed internally of shelves and ramps between floors or corrugated levels. Modern termite nests are constructed in buried fluvial channel, proximal floodplain, and distal floodplain deposits that, at the time of nest building, formed part of a distal floodplain in areas of well-drained soils. Nest architecture varies according to the amount of soil moisture and air humidity. Some termites grow fungus gardens to regulate nest humidity and others build towers to ventilate their nests and regulate the amount of evaporation (Bown 1982; Hasiotis and Bown, 1992). Extant termite mounds can range in height from 2 to 8 m and be 6 to 12 m in diameter. Internally, some nests have runways that can reach depths of up to 6 m or more. Such nests are inhabited by such large numbers of termites that insect molts and feces contribute to most of the volume of the A soil horizon in which they occur (Thorpe, 1949; Wilson, 1971). Ichnofossil termite nests have been described from alluvial rocks in North America, Africa, and South America as old as the Triassic (e.g., Bown, 1982; Sands, 1987; Bown and Kraus, 1988; Bown and Laza, 1990, Genise and Bown, 1994; Hasiotis et al., 1994; Hasiotis and Dubiel, 1995; Hasiotis and Demko, 1996; Hasiotis, in press).

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Ants (Hymenoptera: Formicidae) are the most diverse of all the social insects (Wilson, 1971; Holldobler and Wilson, 1990), and construct complex nests that vary considerably. These organisms also construct their nests in distal floodplains, typically in well-drained soils. Today, ants prefer sandy soils, and can turn over approximately 170 pounds of material per anthill per year (Thorpe, 1949). In a square acre in the American southwest, it is common to find twenty or more nests with a total of up to 1.5 tons of fresh earth brought to the surface— conservative estimate for the ants of the Great Plains of the United States (Wheeler, 1925; Thorpe, 1949). Although ant body fossils are known as early as the early Late Cretaceous in amber from New Jersey and Siberia (Wilson, 1971; Holldobler and Wilson, 1990), fossil ant nests were only recently described from the Paleocene-Eocene Claron Formation in southwestern Utah (Bown et al., 1997) and the Upper Jurassic Morrison Formation in eastern Utah and western Colorado (Hasiotis and Demko, 1996). Modern bees and wasps (Hymenoptera: Apoidea and Vespoidea) construct simple to complex structures (e.g., Williams, 1956; Evans, 1958; Batra, 1966, 1968). Many of these insects construct their nests in well-drained, immature to mature soils, and are typically some of the first organisms to burrow into newly exposed substrates. Ichnofossil bee and wasp solitary and social nests have been described from North American, South American, and African rocks as old as the Triassic (e.g., Brown, 1934; Bown, 1982; Retallack, 1984; Bown and Ratcliffe, 1988; Genise and Bown, 1990, 1991; Hasiotis et al., 1995, 1996).

Organisms and the Intermediate Vadose Zone Many macro- and mesoscopic organisms live and operate in soils that are moist (Schaller, 1968). Crickets (Insecta: Orthoptera), earwigs (Insecta: Neuroptera), caddisflies (Insecta: Trichoptera), soil bugs (Insecta: Hemiptera), spiders (Arachnida), and other

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arthropods construct burrows or nests of varying depths and architectures that are dependent upon soil moisture, water table levels, and other substrate requirements (e.g., Smith and Hein, 1971, Stanley and Fagerstrom, 1974; Chamberlain, 1975, Ratcliffe and Fagerstrom, 1980). The burrowing ability of certain fossorial (i.e., soil-dwelling) insects (e.g., Hemiptera) have been tested with respect to soil types and variable soil moisture regimes (e.g., Gunn and Kennedy, 1936; Willis and Roth, 1950, 1962; Shorey and Gyrisco, 1960; Anderson, 1977). Willis and Roth (1962) demonstrated that the soil moisture content rather than soil type regulates burrowing ability when the insects were placed in soils different from their native habitat. The insects did well with soil moisture contents between 7% and 37%. No burrowing was successfully managed by the insects in soil moistures above or below those levels. Therefore, it is probable that ancient fossorial insects required specific amounts of moisture in their soilburrowing habitats.

Organisms and the Lower Vadose Zone, the Capillary Fringe, and Standing Water Soft-bodied worms, clams, mussels, and gastropods are useful indicators of high and low water tables in the sedimentary units in which they occur. Earthworms are active in sediments above the water table with low to medium soil moisture (e.g., Thorp, 1949; Hole, 1981). Nearly everyone has witnessed the mass exodus of earthworms after heavy rains, in which the worms attempt to escape from death by drowning in their burrows. Earthworm populations are conservatively estimated to modify (or rework) 500-2,500 tons (508-2,540 metric tons) of soil per acre per year (Thorpe, 1949; Schaller, 1968). Other annelid worms and nematodes are fully aquatic and have much smaller body size, and they occur at sites with consistently high water tables, such as streams, rivers, ponds, and lakes. Clams, mussels, and gastropods are aquatic organisms that construct aestivation (dry period) burrows during falling water levels and

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actual desiccation, and they also occur in ephemeral streams and rivers. These creatures usually leave behind crawling and directional traces that follow receding waters (e.g., Pryor, 1967; Chamberlain, 1975; Miller et al., 1981). Many kinds of beetles inhabit a variety of wet and dry environments with moisture levels analogous to the lower vadose zone and capillary fringe, where they construct shelter burrows, dwelling structures, and brood nests. Specific beetle burrows are therefore very useful in deciphering ancient soil moisture and water table levels. For example, mud-loving beetles (Coleoptera: Heteroceridae) construct horizontal burrow traces where the water table is approximately at the surface, whereas dung beetles (Coleoptera: Scarabaeidae) build brood nests in well-drained soils with ample ground litter (e.g., Silvey, 1936; Howden, 1955; Chamberlain, 1975). Fossil beetle nests have been described from crevasse-splay and proximal overbank deposits, and from paleosols (e.g., Bown, 1982; Bown and Kraus, 1983; Retallack, 1984; Hasiotis et al., 1993a; Hasiotis et al., 1994; Genise and Bown, 1994).

Organisms and the Phreatic Zone Few organisms, such as terrestrial and freshwater crayfish, construct burrows through the soil profile to reach a shallow to deep phreatic zone, the top of which is marked by the water table. Today, crayfish occur on nearly every continent with the exception of Africa and Australia. Modern crayfish construct burrows in imperfectly drained soils, where they are as densely packed as 50,000 chimneys (burrow openings) per acre (0.4047 hectares) (Thorpe, 1949). Crayfish burrows reach depths of more than 5 m, and crayfish redistribute as much as 2.5 tons (2.54 metric tons) of soil per acre per year. Other crayfish live in water bodies but can burrow to depths of 4 m or more to escape desiccation (Hobbs, 1981). Hobbs (1981) and Horwitz and Richardson (1986) categorize crayfish according to the amount of time spent in the

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burrow, on the complexity of burrow architecture, and on burrow position with respect to the water table. Therefore, crayfish trace fossils are extremely useful in deciphering ancient water table levels (Hasiotis and Mitchell, 1993; Hasiotis, 1997a; Hasiotis and Honey, 2000). Crayfish burrows and fossils are known from as old as the Triassic (Hasiotis and Mitchell, 1989, 1993). Crayfish burrows without associated body fossils are known from rocks as old as the late Pennsylvanian and Early Permian (Hasiotis et al., 1993b; Hasiotis, 1997a, 1999).

Burrowing Organisms and Soil Development Invertebrates play an active role in soil development by churning and mixing materials between horizons; they are an integral part of soil development. Other soil-forming factors include macro- and microclimate, topography, parent material, and time (Jenny, 1941). Invertebrates also aerate soils and create root pathways by burrowing, often increasing the rate of oxygen exchange within the soils (Hole, 1981). Animal and plant participation in soil development on alluvium in ancient environments has probably been integral from at least the Ordovician (Retallack and Feakes, 1987; Hasiotis and Bown, 1992; Hasiotis, 1997a). Remnants of their activity appear to be preserved in pedogenically altered alluvium from at least the Late Ordovician (e.g., Retallack and Feakes, 1987). Summaries of organisms and their effects on soil formation are presented by Thorp (1949), Schaller (1968), and Hole (1981). Organism-soil activities are substantiated here and in previous papers on observations in neoand paleoichnology (e.g., Brown, 1934, Smith and Hein, 1971; Retallack, 1977, 1984; Behnke, 1977; Bown and Kraus, 1987; Kraus, 1987; Ransom et al., 1987; Sands, 1987; Hasiotis and Mitchell, 1993; Hasiotis et al., 1993a, b). Biologic and pedogenic processes result in the formation of sedimentary discontinuity surfaces of short- to long-term duration. The role of organisms in soil formation is

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characterized by the density of their burrowing activity, the amount of soil turnover, and nutrient contributions. These organisms include ants, termites, sow bugs, beetles, millipedes, centipedes, spiders, earthworms, crayfish, crabs, mammals, amphibians, and reptiles. Although the effects of micro- and mesoscopic organisms cannot be directly seen in paleosols, the effect of macroscopic organisms can be observed by their traces in a soil profile and used to gauge the duration of organism behavior in soil-forming processes (Hasiotis, 1997a, 2000). For example, invertebrates, particularly insects, are known for turning-over millions of metric tons of soil per year (Thorpe, 1949; Hole, 1981). The longer a surface is exposed, the greater is the amount of reworking and soil formation, up to the maximum extent in which all original bedding above the water table is destroyed and soil features (i.e., burrows, roots, blocky structures, slickensides, mottling) develop in place (Hasiotis, 2000; Hasiotis and Honey, 2000). In paleosols, burrows and nests with the greatest preservation potential are those that are constructed and then reinforced, rather than merely excavated. Constructed and reinforced burrows and nests contain organic material acted on during pedogenesis and later by diagenesis, preferentially preserving the structure (Hasiotis and Bown, 1992; Hasiotis et al., 1993a; Genise and Bown, 1994). Burrows constructed by crayfish and crabs also have a great preservation potential that is due, in part, to their size and depth of burrowing (Hasiotis, 1990a; Hasiotis and Mitchell, 1993).

Defining Ichnologic Behavior Based on the distribution of modern burrowing organisms and their physiological requirements for moisture, a six-part division of burrowing behavior categorizes ichnofossils into behavioral groups that reflect different moisture zones of groundwater and space and trophic utilization in the deepest portions of groundwater (Hasiotis, 1997a; 2000) (Fig. 4). Terraphilic

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Terraphilic

Hygrophilic

Unconsolidated sediment

Phreatic Zone

Water in fractures and pores of bedrock; also in chemical combination with rock

Figure 4. Behavioral groups and their relationship to the groundwater profile. From Hasiotis (1997a).

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traces are constructed by organisms living above the water table in the uppermost parts of the soil-water profile to the upper part of the vadose zone. These organisms have low tolerance for high moisture levels and can live in areas with relatively little available water. Epiterraphilic traces occur at or above the surface by surface-dwelling, shallow nesting, nest-mounding, and trackway-making organisms. Hygrophilic traces are constructed by organisms living within the vadose zone with specific physiological and reproductive soil moisture requirements. Hydrophilic traces are constructed by organisms that live at or below the water table within a soil, and at-or within the substrate in open bodies of water, such as rivers and lakes. Cryptophilic traces are constructed by organisms that live in pore spaces between grains and that can alter the sorting of the substrate (T. M. Saunders and M. A. Gingras, personal communication, 1997). Chemophilic traces occur as microendolithic borings and etched surfaces on rock fragments and mineral grains (Staudigel et al., 1995; Hasiotis et al., 2002; J. R. Rogers, personal communication, 2001), as well as chemical or isotopic signatures of bacterial action within pore spaces feeding on organic material within anoxic settings (Moldowan et al., 1992). The combination of tracemakers and their biological requirements pertaining to groundwater help to further differentiate continental depositional settings through the environmental factors controlling the distribution of organisms. The morphology, complexity, and length of the trace fossil, the sedimentary structures, and the pedogenic features of the unit in which the trace occurs will determine to which category the trace is assigned. Although the actual ancient water table is not preserved in the rock record, its position is recorded approximately through ichnology, sedimentology (primary and secondary sedimentary structures), and paleopedology (mottling, ped-structure, coloration, micromorphology, texture, and soil geochemistry) (Retallack, 1990; Hasiotis, 1997a, 2000). For example, both Insecta

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and Crustacea exhibit burrowing behaviors unique to specific subaqueous and subaerial portions of depositional environments. The depth of these traces and their crosscutting relations with other traces (e.g., tiering) within a profile approximate the position of the ancient soil moisture zones and the water table (Hasiotis, 1990b; Hasiotis and Dubiel, 1994). These traces occur in deposits whose primary and secondary sedimentary structures or pedogenic features preserve characteristics of the environment in which the organism was burrowing. Integration of physical, biogenic, and chemical evidence provides information about the paleohydrology. For example, ichnofossil tiering in continental rocks was first described in the Shinarump Member of the Upper Triassic Chinle Formation in northwestern New Mexico (Hasiotis and Dubiel, 1994). The crosscutting and conterminous relations of distinct trace fossil morphologies that represent different organisms that burrowed in sediments with different moisture levels define the tiers. Each tier reflects inter-related aspects of the paleobiologic and paleohydrologic regime: nutrient availability, organism interactions, soil moisture content, and water table level. Thus, the paleoecological tiering in these Triassic continental rocks recorded information about the paleohydrologic regime of the deposits, enhancing Pangean paleoclimatic and paleogeographic interpretations for the lower part of the Chinle Formation. Tiering relations through time can be evaluated in the continental rock record in conjunction with the depositional and tectonic histories to better comprehend paleo-orographic, paleolatitudinal, and paleoclimatic effects across different paleogeographic settings (Hasiotis and Dubiel, 1994).

ICHNOLOGIC FRAMEWORK OF CONTINENTAL ENVIRONMENTS The continental ichnologic realm is divided broadly into alluvial, lacustrine, and eolian depositional environments. Each environment is further divided into subenvironments characterized by suites of sedimentary structures that constitute specific environmental

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components. For example, the alluvial environment is subdivided into channel, levee, crevasse-splay, and proximal to distal floodplain subenvironments (Collinson, 1986a). Temporal factors within each subenvironment must also be considered when subdividing depositional environments. Temporal factors include ephemeral or perennial environments (e.g., pond), and the type and degree of soil development in terrestrial environments. Thus, each depositional environment is divided into subenvironments based on depositional processes and sedimentary structures, degree of pedogenesis, the expression and position of the water table, and relative soil moisture levels (e.g., Hasiotis, 2000). Paleosols are not primary deposits. Paleosols are the result of post-depositional modifications of deposits within alluvial, lacustrine, eolian, and transitional environments (Hasiotis, 2000; Retallack, 2001). Consequently paleosols cannot be used as a subdivision or potential ichnofacies. Pedogenesis modifies nearly all terrestrial surficial deposits produced by depositional environments, and pedogenesis occurs at different rates and with different results depending on the rate and frequency of depositional events, distance from sediment source, parent material, and the position and fluctuation of the groundwater (Bown and Kraus, 1987; Kraus, 1987; Hasiotis and Bown, 1992; Hasiotis, 1997a). Diagrams in the following section illustrate the variability of soil development across different continental environments.

Alluvial Environments Terrestrial and freshwater trace fossils aid the interpretation of the depositional history and paleoecological setting of alluvial environments. Potential alluvial ichnofacies are based on sedimentary deposits and their trace-making inhabitants. Each alluvial subenvironment contains biota uniquely adapted to that setting (Fig. 5). These potential ichnofacies also

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Figure 5. Characteristics of Alluvial subenvironments and their variations. From Hasiotis (1997a).

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represent ecological partitions founded on the vertical and lateral expression of water table and soil moisture levels and biotic components across the alluvial environment. The alluvial environment is partitioned naturally into at least four depositional and ecologic categories: (1) channel, (2) levee and proximal floodplain, (3) crevasse-splay, and (4) distal floodplain. These four subenvironments can be further subdivided according to the kind and degree of pedogenic modification. The divisions exemplify distinct suites of depositional energy, grain sizes, sedimentary structures, paleosol development, and hydrologic regimes.

Channel Subenvironment Channels undergo fluctuating energy and water levels, and support abundant aquatic invertebrates that generate biogenic structures such as resting, dwelling, and reproductive traces (e.g., Chamberlain, 1975; Hasiotis and Bown, 1992; Hasiotis, 1997a). Most aquatic invertebrate burrows are constructed in various kinds of channel bars. The greatest diversity of organisms is near channel margins, where stream velocities are lower and nutrient availability is higher (e.g., Stagliano and Benke, 1996). Organism activity is preserved in channel bottoms during periods of no sedimentation or in abandoned channels (e.g., Pryor, 1967; Toots, 1967; Smith and Hein, 1971; Stanley and Fagerstrom, 1974; Bromley and Asgaard, 1979; Miller et al., 1981). In channel deposits, traces delineate benthic organism diversity, water level (table) depths, and point-bar orientation and meander-migration direction. Through time, shallow and deep burrowers effectively homogenize the sediment and destroy bedding, especially if the water table fluctuates. Organisms inhabiting channels include gastropods, nematodes, bivalves, crayfish, crabs, insect larvae (mayflies, caddisflies, stoneflies, and dragonflies), mud-loving beetles, aquatic oligochaetes, and other aquatic and terrestrial crustaceans and insects (e.g., Chamberlain,

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1975). The majority of traces constructed by these invertebrates are developed at or below the water-sediment-air interface, and most are horizontal. Also constructed above the water table are burrows of amphibians and mammals (e.g., Chamberlain, 1975). Where the water table has dropped, exposing bars and channel bottoms, vertical burrows constructed by aquatic and terrestrial organisms are abundant and well-developed (e.g., Pryor, 1967; Hasiotis and Bown, 1992). Burrows in these strata are categorized as shelter burrows (vertical), deposit-feeding burrows (horizontal and shallow U-shaped), vertical passageways (between organic-rich layers), directional surface traces, and temporary refuges (Stanley and Fagerstrom, 1974).

Levee and Proximal Overbank Subenvironment Levee and proximal overbank deposits result from channel flooding overbank areas, and are generally marked by alternating beds of sand and mud. These sediments may coarsen or thicken upwards and generally fine away from the channel depending on the direction of channel-migration and channel configuration (Collinson, 1986a; Elliot, 1986). Levee and proximal overbank areas experience repeated emergence and near emergence; thus, the ichna illustrate cycles of fluctuating water tables and entrapment of organic material. The biological prerequisites for invertebrates and plants inhabiting levee and proximal overbank areas are reflected by the burrows and style of rooting. The types of behavior represented by traces include deposit-feeding, shelter, dwelling, and reproduction, all of which are regulated by the physiology of an animal and its spatial interaction with the water table. Overprinted burrows from fluctuating high and low water tables and moisture levels are well-represented in these deposits, reflecting periods prior to (terraphilic), during (hydrophilic), and after (hygrophilic to terraphilic) flooding.

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In the Eocene-Oligocene Jebel Qatrani Formation of Egypt, ichnofossils of wasps, decapods (crayfish?), and rodents were constructed in channel and overbank sediments during periods of low water tables. These, in turn, were overprinted with a myriad of horizontal, shallow vertical, and U-shaped burrows constructed by insect larvae excavated when the water table was at or above the surface (Bown, 1982; Bown and Kraus, 1988). In other ancient levee and proximal overbank deposits, crayfish, beetles and other insects, worms, and rhizoliths have contributed significantly to bioturbation (e.g., Toots, 1967; Tasch, 1976; Turner, 1978; Ratcliffe and Fagerstrom, 1980; Bown and Kraus, 1983; Hasiotis and Dubiel, 1994; Hasiotis and Demko, 1996; Hasiotis, in press b). In modern settings, backfilled burrows rarely, if ever, are visible in the substrate. Upon early (i.e., increased pedogenesis) and late diagenesis, backfilled meniscate burrows become obvious due to preferential alteration of the organic material (i.e., feces, secretions, etc.) associated with the burrow (Hasiotis, 1997a).

Crevasse-Splay Subenvironment Crevasse-splay complexes contain overprinted ichna of hydrophilic (high water table) and terraphilic (low water table) organisms. These depositional complexes are short-lived and dominant from the proximal to the distal floodplain, depending on flooding intensity. When crevasse-splay sediments are deposited, they are generally saturated. Initial infaunal components are dominated by transported aquatic and semi-aquatic organisms with behaviors reflected in crawling traces and horizontal and shallow U-shaped burrows constructed by aquatic insect larvae and worms, and semi-aquatic mud-loving beetles (Heteroceridae). Escape burrows produced by aquatic organisms buried by the splay sedimentation are also common features and contribute to the initial fauna. Following infiltration and evaporation of

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the standing water, reduced sediment moisture allows organisms such as annelids and beetles and other insects to take advantage of newly available ecospace by constructing vertical and horizontal burrows. These organisms immigrate from outside the area covered in splay sediments or move upward from the sediment if they have managed to keep from drowning within the soil. For example, the lower Eocene Willwood Formation contains the earthworm trace Edaphichnium, large-diameter vertical burrows, and roots in mud-rich and sand-rich crevasse-splay deposits, signifying a relatively lower water table than immediately after deposition (Bown and Kraus, 1983; Hasiotis et al., 1993a).

Distal Floodplain Subenvironment The distal floodplain is inhabited by invertebrates adapted to terrestrial life where the water table is quite variable, but relatively deep compared to more proximal environments. Soil moisture across a distal floodplain depends on the texture and structure of the soil (sediment), topography, and the frequency and magnitude of flooding events (reflecting climate). Organisms in distal floodplain sediments include crayfish, crabs, earthworms and other annelids, termites, ants, bees and wasps, beetles, spiders, and other fossorial insects and terrestrial plants. When poorly-drained distal floodplains are inundated due to heavy precipitation and flooding, many areas have standing pools of water. These temporary water bodies commonly harbor transported aquatic invertebrates and vertebrates or opportunistic organisms (e.g., flying insects laying eggs). In these ephemeral settings, large numbers of mud-loving and aquatic organisms construct horizontal burrow networks for feeding and habitation. Gastropods and clams construct grazing and feeding burrows before the construction of aestivation burrows, in which their body fossils are rarely preserved because they are temporary shelters until the next wet season and aerated substrates promote decay of

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organic material, including aragonite shells. In some instances, distal floodplain deposits are superimposed with ichna characteristic of ephemeral river and lake subenvironments. Likewise, terraphilic traces, including rhizoliths, would be superimposed on hydrophilic traces in proximal deposits in ephemeral alluvial and lacustrine environments during the dry season.

Lacustrine Environments Unfortunately, lacustrine environments are highly variable, and, in general, less is known about the ichnologic composition of lakes in the geologic record compared to other environments, with the exception of the Green River-type lakes, Triassic lacustrine-deposited strata, and the Triassic-Jurassic rift basins in North America (e.g., Bromley and Asgaard, 1979; Allen and Collinson, 1986; Olsen et al., 1996; Gierlowski-Kordesch, 1991; and references therein). Many lacustrine ichna and facies described from the geologic record, particularly the Carboniferous (e.g., Buatois and Mangano, 1993, 1995; Buatois et al., 1996), are atypical because their sedimentologic and ichnologic components are unlike those of well-studied ancient and modern lacustrine environments. For example, lacustrine rocks of the lower part of the Eocene Green River Formation yield diverse faunal and floral assemblages, but the upper part of the formation is nearly barren because it has saline precipitates (Allen and Collinson, 1986, and references therein). In another example, lacustrine systems of the Upper Triassic Chinle Formation of the Colorado Plateau and the Triassic-Jurassic Newark Supergroup rift basins have been well studied (e.g., Stewart et al., 1972; Dubiel et al., 1991; Olsen et al., 1996; Gierlowski-Kordesch, 1991; and references therein); however, few traces are described from these deposits. Thus, erecting useful lacustrine ichnocoenoses is difficult. The most useful studies of ichna in lacustrine systems are Silvey (1936), Moussa (1970), Gibbard and Stuart (1974), Gibbard and Dreimanis (1978), Bromley and Asgaard (1979), Fisher

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Figure 6. Characteristics of Lacustrine subenvironments and their variations. From Hasiotis (1997a). 31

et al. (1980), Fisher (1982), Tevesz and McCall (1982), and Cohen (1984). These studies examine the relationship between trace-making organisms and environmental processes. Lake size (depth, fetch, etc.), lake level fluctuations, basin configuration (endorheic or exorheic), nutrient availability (oligotrophic, mesotrophic, eutrophic), biodiversity patterns, climatic settings, and distribution of trace-making organisms (Silvey, 1936; Gibbard and Dreimanis, 1978; Fisher, 1982) subdivide ichna and lacustrine environments into three potential ichnofacies: 1) Outer Shoreline; 2) Inner Shoreline; and 3) Permanent Benthos (Fig. 6). These subenvironments vary with each type of lacustrine environment and may not exist simultaneously. For example, if a lake changes in depth and salinity or dries up, as with postglacial lakes of the southwestern and northeastern United States (e.g., Allen and Collinson, 1986, and references therein), the ichnological and sedimentologic signatures would reflect this change. The ichnologic signatures of post-glacial lake deposits would record a lake dominated by inner shoreline and permanent benthos environments that, through time, became dominated by outer shoreline and inner shoreline environments with increased salinity of the water; however, detailed studies like this have not been done.

Outer Shoreline (Supralittoral-Littoral) Subenvironment The outer shoreline of a lake encompasses the outer and middle beach zones of Silvey (1936), which are equivalent to the supralittoral and littoral zones of Brinkhurst (1974) and Wetzel (1983). The outer beach is usually dry to some depth (1 to 10 m) below the surface, and is subject to reworking by winds if not stabilized by vegetation. The outer beach is affected by wave action and splashing during violent storms. The middle beach is typically dry at the surface but is saturated just below the surface. The outer shoreline environment terminates at the furthest extent of swash and backwash (at the saturated water line during calm periods).

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Trace-making organisms of the outer shoreline include: (1) beetles, ants, bees, wasps, other insects and their larvae, and arachnids; (2) crayfish and crabs; and (3) mammals, birds, and reptiles not physiologically dependent on the water table. This latter group of organisms can either vacate their dwellings or can withstand short periods of submergence, or make their way (leaving trackways) to the nearest water body during periods of low water levels. Burrow architectures range from shallow vertical and horizontal burrows to deep vertical burrows with or without chambers at their bases. These burrow architectures reflect relatively lower water table depths compared to the inner shoreline and permanent benthos subenvironments (e.g., Chamberlain, 1975; Ratcliffe and Fagerstrom, 1980; Hasiotis and Bown, 1992), as well as the stability and history of the groundwater profile, which is a function of the lake-basin type (e.g., Bohacs et al., 2000).

Inner Shoreline (Littoral-Sublittoral) Subenvironment The inner shoreline extends from the edge of the saturated zone (100% pore water at the surface) to the basinward position of the shoreline exposed during the maximum period of low water level caused by ephemeral (or seasonal) conditions. This environment is equivalent to the lower beach zone of the littoral zone (Brinkhurst, 1974; Wetzel, 1983). The aerial extent and stability of this subenvironment is a function of the lake-basin type (e.g., Bohacs et al., 2000). Ichna inhabiting the inner shoreline are affected by variable amounts and intensity of wave action, influx of organic material and sediments (increased turbidity), and periods of desiccation and possible eutrophic conditions. The most depositionally active areas of the shoreline contain almost no infaunal organisms or plants due to large fluxes of sediment and wave energy. In less active, inner shoreline areas, a few insects with high water table affinities

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are present, indicated by burrows of mud-loving beetles, insect larvae, horizontal feeding/ foraging traces, mole crickets, spiders, oligochaetes, conchostracans, isopods, or amphipods. Also in this subenvironment, shallow and simple to complex burrow architectures are produced by two different types of burrowing crayfish, or possibly crabs if present. Dry seasonal conditions commonly result in low water levels, where the distal portion of the inner shoreline facies experiences a deepening of burrow lengths and a shift of biota toward the receding strand-line. New, open ecological niche space becomes available to both the outer shoreline and inner shoreline communities. Insect and crustacean burrowing communities from the outer shoreline facies shift basinward and overprint previously constructed traces in sediments of the inner shoreline environment. The invading organisms act as opportunistic faunas on the new and available resources in deeper tiers in freshly exposed areas with shallow- and deep-tiered burrows. The inner shoreline communities also shift basinward, producing shallow burrow systems in previously deeper water environments. When wet seasonal conditions result in high water levels, the exact opposite shifts in communities and overprinting ichna occur.

Permanent Benthos (Sublittoral-Profundal) Subenvironment The permanent benthos is defined as the area of a lake not affected by ephemeral or seasonal low water conditions. This subenvironment includes the lower littoral, littoriprofundal, and profundal zones (Brinkhurst, 1974; Wetzel, 1983). It contains benthic faunas reaching to the deepest portions of a lake. The rationale for lumping the remaining lacustrine subenvironments is that the macrobenthic organisms in lakes are numerically dominated by only a few organisms that do not vary in abundance or diversity due to water depth (Fisher, 1982). The sedimentology of the subenvironments may be distinct to further subdivide the

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physical subenvironment, but the ichna would not be differentiated due to the relatively uniform environmental conditions. The biota in this portion of the lake contains some combination of aquatic insects (e.g., caddisflies and dragonfly larvae), aquatic annelids and nematodes, ostracodes, gastropods, clams, mussels, crayfishes, crabs, and possibly shallow burrowing vertebrates (e.g., fish, turtles, frogs). If a lacustrine basin is sufficiently large, the permanent benthos can be separated into two distinct ecological partitions, and thus potential ichnofacies: one above and one below the photic zone. The photic zone is delineated by the limit of submergent plants and root mats. Ichna below the photic zone are characterized by a lack of plants and thus, rhizoliths, and by both high abundance and low diversity of ichna.

Eolian Environments Modern eolian deposits occur in four major settings throughout the world: (1) Saharatype continental deserts; (2) areas of significant pyroclastic deposition; (3) intra-continental basins; and (4) coastal margins of the transitional zone (e.g., Glennie, 1970; Reading, 1986). Depending on where eolian deposits form, a number of subenvironments can be identified from the morphology of dune fields and their internal stratification. Only intra-continental basin dunes and coastal transitional zone dune fields are examined here, because these two types of eolian deposits are the best studied in both the modern and the geologic record. The key to defining divisions in eolian environments is to understand space and resource partitioning in modern dune fields (Crawford, 1981, 1991). Macro- and microenvironments in continental dunefields establish the biological prerequisites necessary for life: groundwater levels, aridity, thermal extremes, and adaptations in productivity and food webs (Fig. 7). Organism behavior (e.g., reproduction, aestivation, hibernation, vegetation patterns) in modern

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Figure 7. Characteristics of Eolian subenvironments and their variations. From Hasiotis (1997a).

dune fields can be used in ancient examples to divide specific environments by examining burrow architectures, suites of burrow occurrences, and depositional conditions (e.g., Rafes, 1960; Kocurek, 1981; Collinson, 1986b; Crawford and Seely, 1987; Bown and Larriestra, 1990; Crawford, 1981, 1991; McLachlan, 1991; Warburg, 1992). Biogenic traces are common in modern eolian deposits, but the majority has low preservation potential because of dune depositional processes and dune migration. Preservation potential increases when: (1) traces occur in areas where the water table is at or above the surface in interdune areas; (2) rainfall and dampness (dew) allow the sand tobecome cohesive sufficiently to preserve trails by subsequent grain fall; (3) burrows are reinforced by the organism; (4) traces are preferentially cemented (i.e., rhizoliths); or (5) traces are rapidly buried, especially at the toes of the dune slipfaces. An important study on modern dune field bioturbation is that of Ahlbrandt et al. (1978), who examined both coastal and inland dunes for the diversity, abundance, and burrowing behavior of organisms. The purpose of the study was to better characterize ancient eolian deposits by examining modern eolian systems and their inhabitants. Ahlbrandt et al. (1978) concluded that arthropod burrows are abundant because arthropods represent 75% of the modern Animal Kingdom and that their traces are similar to those found in Permian eolianites. Ahlbrandt and Fryberger (1982) recognized three major subenvironments, including dune, interdune, and sand sheet, but they were unable to define associations between particular trace-making organisms coinciding with their subdivisions. Arthropods found in dune fields existed in all three partitions, but their burrow architectures and associated biota were useful in discriminating subenvironments, particularly in the case of wet interdune (Hasiotis, 1997a). Ancient eolian deposits, “eolianites”, commonly have a meager record of both body fossils and ichnofossils (Ekdale et al., 1984). Body and trace fossils preserved in these deposits include:

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(1) dinosaurs and mammals and their tracks; (2) insect, arachnid, and scorpion tracks, trails, and burrows; and (3) ostracodes, clams, gastropods, fish, and their trails and burrows. Ahlbrandt et al. (1978) also evaluated the geologic significance of bioturbation in eolianites by comparing and contrasting the types of traces and the geologic ranges of the organisms that constructed them. They found that bioturbation is common in many, if not all, modern dunefields, and should be found in nearly all eolianites as old as the Carboniferous. The only problem is that preservation potential is low unless desert surfaces are moist, wet, or directly associated with the water table. The observations of Ahlbrandt et al. (1978) are in accord with those of Crawford (1991), who suggested that, collectively, dunefield environments are harsh, but surprisingly rich in biota built successfully on “stable” micro-environments through special adaptations in morphology, food webs, and community strategies. For the most part, eolian deposits can be divided into three potential ichnofacies, each with specific biological prerequisites that limit faunal and floral occupants: (1) dunes (represented by slipfaces), (2) dry interdunes, and (3) wet interdunes (Fig. 7). With increasing study of modern and ancient dune fields, the list of taxa and traces within each partition will increase.

Dune Subenvironment Burrows of sand wasps, crickets, crane fly larvae, beetles, and wolf spiders, along with molds of root are found on dune slipfaces and stoss sides (Ahlbrandt et al., 1978). Also found here are burrows of mammals such as rodents (e.g., Bown and Larriestra, 1990). Typical sedimentary structures include wind ripples, grainfall lamination, grainflow cross-stratification, and dune foresets (e.g., Kocurek, 1981; Collinson, 1986b).

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Dry Interdune Subenvironment Dry interdune areas contain ant nests, termite nests, crane fly larvae burrows, rodent burrows, and root molds (Ahlbrandt et al., 1978). This subenvironment is characterized by wind ripples, eolian foresets, lag surfaces, deflation scours, and sand drift features (Kocurek, 1981).

Wet Interdune Subenvironment Wet interdune areas contain water-dependent faunal and floral assemblages not found elsewhere in dune-field systems. Animal traces include gastropod and toad aestivation burrows, larval traces of flying insects (e.g., dipterans), tracks and trails of vertebrates (reptiles and mammals), and invertebrates (gastropods, arthropods of various types) (Ahlbrandt et al., 1978). Also present are rhizoliths of various size, shape, and depth. These organisms make up distinct ecologic associations because they represent areas where the water table was at or above the surface. The wet interdune is also distinctive in lithology (very fine grained, waterand wind-laid sand) and stratification indicating the preservation of water-generated structures, such as symmetrical and asymmetrical ripples, algal structures, mud-cracks, rill marks, channels, and small deltas (e.g., Kocurek, 1981). An important note is that when erg systems encroach areas of high water tables, wet interdunes may be abundant early in the record of that system. As time passes, the local climate and regional hydrologic settings will reflect drier climates due to modifications (i.e., increase in albedo, higher temperatures and evaporation rates, much fewer plants, etc.) of the environment due to development and migration of the erg system (e.g., Ahlbrandt et al., 1978; Collinson, 1986b).

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Dune Fields in the Transitional Zone In coastal dune fields, sand movement, salt spray, and wind and storm disturbances are physicochemical stresses on biota and flora (e.g., Ardo, 1957; Hill and Hunter, 1976; Fouch and Dean, 1982; Skiba and Wainwright, 1984; Cloudsley-Thompson, 1987; McLachlan, 1991). These dune fields are ecologically differentiated into three groups: (1) transitional zone dunes, (2) coastal-bound dunes (slipfaces affected by spray, fog, and large storms), and (3) terrabound dunes and interdunes (affected by fog and precipitation). McLachlan (1991) summarized the importance and uniqueness of modern coastal dune fields and the physical and biological components that have direct bearing on the differentiation of seaward and landward organisms (ichnofaunas) of the transitional zone between marine and continental environments. The biota inhabiting transitional dune field environments respond to groundwater, salinity, nutrient, and energy gradients across the beach/dune interface. For example, insects, vertebrates, and other infaunal organisms increase in abundance landward because of an increase in vegetation diversity, soil development, and substrate stability. Marine crustaceans decrease landward because of the decrease in the seawater/fresh groundwater table gradient and greater fluctuations in temperature and moisture. Changes across the transitional zone reflect ichnofaunal responses to physical, chemical, and biological characteristics as ecological gradients (Fig. 8).

SUMMARY Continental environments contain a vast of amount of biota in varying degrees of diversity and abundance. The burrowing behavior of these organisms (including plants) can help differentiate subenvironments within alluvial, lacustrine, and eolian environments. Understanding ichnofossils and their relation to sedimentary units allows greater interpretation of the depositional and post-depositional histories of sediments and the environmental and 40

Figure 8. Characteristics of eolian transitional environments and interactions between marine and continental systems. Modified from McLachlan (1991).

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climatic settings under which they formed. Continental ichnology is another tool geoscientists can use in the field or laboratory (studying cores) that will make the difference in determining continental from marine environments, floodplain from profundal lacustrine environments— settings that are ichnologically distinct.

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Seilacher, A., 1967. Bathymetry of trace fossils. Marine Geology, 5:413-428. Shorey, H. H. and Gyrisco, G. G. 1960. Effects of soil temperature and moisture on the vertical distribution of European chafer larvae. Ann. Ent. Soc. Amer., 53:666-670. Silvey, J. K. G. 1936. An investigation of the burrowing inner-beach insects of some fresh-water lakes. Mich. Acad. Sci. Arts Letters Pap., 21:655-696. Skiba, U. and Wainwright, M. 1984. Nitrogen transformation in coastal sands and dune soils. Journ. Arid Environ., 7:1-8. Smith, R. M. H. 1987. Helical burrow casts of therapsid origin from the Beaufort Group (Permian) of South Africa. Palaeogeography, Palaeoclimatology, Palaeoecology, 60:155-170. Smith, N. D. and Hein, F. J. 1971. Biogenic reworking of fluvial sediments by staphylinid beetles. Journ. Sed. Petrol., 41:598-602. Stagliano, D. M. and Benke, A. C. 1996. Diversity and emergent production of an insect community at the land-water interface of a southeastern wetland. North American Benthological Society Meeting, May, 1 p. Stanley, K. O. and Fagerstrom, J. A. 1974. Miocene invertebrate trace fossils from a braided river environment, western Nebraska, U.S.A. Palaeogeogr., Palaeclimat., Palaeoecol., 15:63-82. Staudigel, H., Chastain, R. A., Yayanos, A., and Bourcier, W., 1995. Biologically mediated dissolution of glass. Chemical Geology, 126:147-154. Stewart, J. H., Poole, F. G. and Wilson, R. F. 1972. Stratigraphy and origin of the Chinle Formation and related Upper Triassic strata in the Colorado Plateau region. U. S. Geol. Surv. Prof. Pap. 690, 336 p. Tasch, P. 1976. Jurassic nonmarine trace fossils (Transantarctic Mountains) and the food web. Journ. Paleont., 50:754-758. Tevesz, M. J. S. and McCall, P. L. 1982. Geological Significance of aquatic nonmarine trace fossils, p. 257-285. In McCall, P. L. and Tevesz, M. J. S., eds., Animal-sediment relations: The biogenic alteration of sediments. Plenum Press, New York, 336 p. Thorpe, J. 1949. Effects of certain animals that live in soils. Scient. Month., 68:180-191. Toots, H. 1967. Invertebrate burrows in the non-marine Miocene of Wyoming. Wyoming Univ. Contr. Geol., 6:93-96. Turner, B. R. 1978. Trace fossils from the Upper Triassic fluviatile Molteno Formation of the Karoo (Gondawana) Supergroup, Lesotho. Journ. Paleont., 52:959-963. Valentine, J. W. (ed.). 1985. Phanerozoic Diversity Patterns—profiles in macroevolution. Princeton University Press, Princeton, 441 p.

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Villani, M. G., L. L. Allee, A. Diaz, and P. S. Robbins. 1999. Adaptive strategies of edaphic arthropods. Annual Review in Entomology, 44:233-56. Vittum, P. J., M. G. Villani, and H. Tahiro. 1999. Turfgrass Insects of the United States and Canada, 2nd edition. Cornell University Press, Ithaca, 422 p. Voorhies, M. R. 1975. Vertebrate burrows, p. 325-350. In Frey, R. W. (ed.), The Study of Trace Fossils, Springer Verlag, New York Inc., 576 p. Warburg, M. R. 1992. Reproductive patterns in three isopod species from the Negev Desert. Journ. Arid Environ., 22:73-85. Wetzel, R. G., 1983, Limnology, 2nd edition. Saunders College Publishing, Philadelphia, PA, 767 p. Wheeler, W. M. 1925. Ants: their structure, development, and behavior. Columbia University Press, New York, 663 p. White, C. D. 1929. Flora of the Hermit shale, Grand Canyon, Arizona. Carnegie Institute of Washington Publication, 405, 221 p. Wiggins, G. B., 1977, Larvae of the North American Caddisfly Genera (Trichoptera). University of Toronto Press, Ontario, Canada, 401 p. Williams, F. X. 1956. Life History studies of Pepsis and Hemipepsis wasps in California (Hymenoptera, Pompilidae). Ann. Entomol. Soc. Am. 49:447-466. Willis, E. R. and Roth, L. M. 1950. Humidity reactions of Tribolium castaneum (Herbst). Journ. Exptl. Zool., 115:567-587. Willis, E. R. and Roth, L. M. 1962. Soil and moisture relations of Scaptocoris divergins Troeschner (Hemiptera: Cynidae). Ann. Entomol. Soc. Amer., 55:21-32. Wilson, E. O., 1971. The Insect Societies. Belknap Press, Harvard University, Cambridge, Massachusetts, 548 p. Wing, S. L., Hasiotis, S. T., and Bown T. M. 1995. First ichnofossils of flank-buttressed trees (late Eocene), Fayum Depression, Egypt. Ichnos, 3:281-286.

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OUTCROP AND CORE ATLAS

Modern termite nest

Jurassic termite nest

Jurassic termite nest

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INTRODUCTION Trace fossils are presented alphabetically by the type of organism thought to have constructed the burrow, trail, trackway, or nest. Such trace fossils as adhesive meniscate burrows and U-shaped burrows are listed separately because of their distinct morphologies. Rhizolith and vertebrate traces are also included. Each section has a description; interpretation of the behavior of the tracemaker and significance of the structure(s); its geologic range; trophic classification; and environmental and climatic implications. The traces are illustrated with idealized line drawings as seen in outcrop and in core. Color photographs depict trace fossils in hand specimens, outcrop, and core from different geologic formations and ages. Many of these traces occur in paleosols, where differences in color between the trace fossils and surrounding matrix accentuate the trace fossil’s morphology. This format allows the user to determine what the trace fossil he or she is working with as well as what the paleoenvironmental and paleoclimatic settings were of the accompanying strata. The last two pages in this section (pages 131–132) are summary sheets of the trace fossil and contain representative color photographs and line drawings of each trace fossil in the photoglossary. It is organized by the orientation of trace fossils in outcrop (or core), and the morphologic complexity of the traces. The summary sheets can also be referred to by the user to key a trace fossil morphology into a particular section in the photoglossary. This sheet also includes a list of abbreviations of continental trace fossils to be used when measuring sections in the field or describing core at an offsite location. The addition of these summary sheets allows you to have your guide to continental trace fossils readily available wherever you go. A separate, laminated reference sheet of these two pages is available from SEPM at www.sepm.org. The laminated sheet is SEPM Product 55004.

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TRACE FOSSILS

Key for Abbreviations

AMB Ac At Ar Ca Ce Ck Cp Dt Dp Ea Ed Fy Fu Hp H/V Is Km Mn Pb Ps Pe Pl Rh Sm Sl So St Tk Tm Ur Ve Vt Wp

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Adhesive meniscate burrows Ancorichnus Ant nest Arenicolites Camborygma Celliforma-bee nest/cells Cochlichnus Coprinisphaera Dinoturbation Dipteran traces Eatonichnus Edaphichnium Flying traces Fuersichnus Haplotichnus horizontal/vertical burrow Isopodichnus Kouphichnium Macanopsis Paleobuprestis Paleoscolytus Pelecypodichnus Planolites Rhizoliths Scaphichnium Scolicia Scoyenia Steinichnus Tektonargus Termitichnus Uruguay-bee nest Vertebrate burrow Vertebrate track Wasp nest/cocoon

ADHESIVE MENISCATE BURROWS (AMB) Description: Horizontal to vertical burrows characterized by backfill menisci that are thin (< 1mm) and packed either loosely or tightly with little space between the backfill. Burrows may or may not have a discrete wall bounding the menisci. These burrows are termed "adhesive" by Bown and Kraus (1983) because the backfill does not weather in bos relief or is not differentially weathered from the rest of the burrow. Chambers are sometimes found within or at the end of the menisci trail. The chamber has a well-defined wall that may or may not be perferated by more meniscae. The chamber is commonly the same diameter as the trail, or may be slightly wider. The height of the chamber is usually 1:1 to 1.5:1 the the burrow width. The AMBs superficially resemble the marine trace fossils Taenidium and Muensteria. If the traces contain alternating fine and coarse-grain sizes and weather in bos relief, then refer to Scoyenia, Ancorichnus, and back-filled burrows (BFB). Interpretation: The pattern represented by the menisci and the related chambers are most distinctive of the behavior of extant soil bugs (Insecta: Hemiptera) and beetles (Insecta: Coleoptera). The traces likely represent the locomotion and feeding behavior of larvae moving through the soil substrate; they would be feeding on roots and other organic debris (Willis and Roth,1962; Villani et al., 1999). The chamber and its well-defined wall are likely due to the larvae compacting the walls by a twisting motion of its body, which compacts its feces and sediment to form a wall. Some larvae will secrete a mucous that cements the compacted soil and feces in the wall prior to pupation (Villani et al., 1999). Geologic Range: Permian to Recent (Hasiotis and Bown, 1992; Hasiotis and Demko, 1996). Trophic Classification: Adhesive meniscate burrows represent foraging behavior of the nymphal and adult stage in soil bugs (Insecta: Hemiptera) and the larval stage in beetles (Insecta: Coleoptera). The chamber(s) associated with the trail represent the transformation of larvae to adult (complete metamorphosis in beetles). Chambers of soil bugs represent resting stages during molting. Several chambers in one trail may repesent stages in prepupal molting. Environmental & Climatic Settings: The architecture of traces usually reflect 10-37% soil moisture typically found in the A and upperparts of B horizons in soils. The adhesive nature of the burrow reflects higher soil moisture, presence of organics, and relatively uniform grain sizes. These traces are found in proximal to distal alluvial and marginal-lacustrine environments. Deeper AMB reflect lower soil moisture and water table levels in those substrates. The insects will move up and down in the substrate to stay within appropriate moisture ranges. Traces in areas of high water table tend to be very shallow. A food source (i.e., plant roots) must be present in order for these organism to be present in the soil. paleosurface

chambers

meniscae 1 cm

Cross-sections of AMB 4" diameter core

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ADHESIVE MENISCATE BURROWS (AMB)

A

B

C D

E

2 cm Adhesive meniscate burrows (AMB): A) Outcrop plan-view of AMB, Lower Eocene Willwood Formation, Worland, Wyoming. B) Cross-section in core of AMB with chambers, Salt Wash Member, Upper Jurassic Morrison Formation, Green River, Utah. C) Outcrop cross-section view of a paleosol with AMB (dark blebs) with rhizoliths and crayfish burrows, Shinarump Member, Upper Triassic Chinle Formation, Ft. Wingate, New Mexico. D) Cross-section of mature paleosol with crosscutting AMB, Owl Rock Member, Upper Triassic Chinle Formation, Ghost Ranch, New Mexico. E) Outcrop plan-view of AMB in moderately developed paleosol, Miocene alluvial deposits, Montsarrat, Spain.

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ANNELID TRAILS - COCHLICHNUS Description: Simple, regular, meandering sinusoidal trails that range in thickness from 0.10.3 cm and can reach lengths of 30+ cm. The trail resembles a sine curve. The range of the trail width suggests that more than one type of animal makes this form. This trail is often confused with Haplotichnus isp., an irregularly, crooked meandering trail that sometimes loops on itself. Interpretation: These traces are produced by annelids--nematodes to aquatic oligochaetes-that are most common in and around streams, ponds, rivers, and lakes. The thin meandering trails are produced by nematodes while the thicker, and typically shorter trails are produced by aquatic oligochaetes (Hitchcock, 1858; Hasiotis and Bown, 1992). Both trails represent movement along or just below the substrate-air-water interface in a thin film of water typically less than 1mm in depth. Geologic Range: Carboniferous to Recent (Hantzschel, 1975; Hasiotis and Bown, 1992; Hasiotis, 1997a). Trophic Classification: The trails represent locomotion in aquatic annelids. Environmental & Climatic Settings: These traces are found in aquatic portions of alluvial and lacustrine environments, particularly in channels, floodplain ponds, and the shallow littoral zones of lakes. They form under quiet water settings, particularly in areas that are frequently inundated by water. They are indicators of perennial freshwater aquatic environments; even though they are in places with thin water-films, they are part of a perennial system. These traces are evidence that the water table was above the land surface. Climatically, nematodes are found in temperate and tropical zones as well as in Antarctica. Oligochaetes occur in the same range (but not in Antarctica) as nematodes and are less abundant in colder climates where permafrost is present.

1 cm

plan view of trails

4" diameter core

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ANNELID TRAILS - COCHLICHNUS

A

B

5 cm

5 cm

C

D

Ha

Co

5 cm

5 cm

Cochlichnus-Annelid Trails: A) Cochlichnus isp. in littoral interdistributary lacustrine, channel sandstones, Tidwell Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. B) Cochlichnus isp. with a pterosaur track (below lens cap) in littoral lacustrine, interdistributary channel sandstones, Tidwell Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. C) Cochlichnus isp. with pterosaur tracks (circles) in littoral lacustrine, splay sandstones, Tidwell Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. D) Modern sinuous trails similar to Cochlichnus isp. (Co-middle of photograph-outlined) constructed by nematodes in very shallow water (< 1 mm depth). Note the Haplotichnus isp. (Ha) associated with Cochlichnus isp. These traces where constructed along the banks of the Purgatoire River, Colorado, after high flow stage (now drying out in photograph).

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COCHLICHNUS VS. HAPLOTICHNUS TRAILS

A

B

5 cm

Haplotichnus Trails: A) Haplotichnus isp. in littoral lacustrine, interdistributary channel sandstones, Upper Eocene Uinta Formation, Myton, UT. B) Haplotichnus isp. traces where constructed along the banks of a creek in the Henry Mountains, Cass Creek Pass, UT, after high flow stage (now drying out in photograph). These traces are constructed by either small insect larvae or very small spiders.

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ANT NESTS Description: Mosaic patterns of spatially distributed networks of galleries (tube, length >>> width) and polydomal chambers (length = > width = > height). Chambers range in number from 10 to over 1000, although the number visible in core or outcrop will vary with exposure and ontogenic stage (new vs. old) of the nest. Polydomal chambers are hemispherical to oblate. Galleries are connected to chambers and to other galleries; they are 0.5-3.0+ cm in diameter. This mosaic pattern can range anywhere from < 1m2 to over 3 m2 in surface area and 3 m in depth. The galleries form a grid-like lattice around a central cluster of chambers and the surrounding area. Interpretation: The pattern represented by the chambers and galleries are those most distinctive of nest patterns constructed by extant species of ants (Hymenoptera: Formicidae). Nests are subterranean with small portions above the surface, but nests also occur in dead and living trees and plants. The ant nests reflect social behavior and division of labor among the colony, with workers, soldiers, winged reproductives, and a king and queen. Ants use their nests as storage for grains and plants materials collected from the surface, for fungal gardens, for egg-rearing, and nurseries, and for the storage of dead ants and wastes. Geologically older nests also show evidence of social behavior and a division of labor, but there may be very little phenotypic difference between the castes. Modern ant nests vary considerably in size from under 1 m2 to over 100-1000+ m2 and 10+ m deep, like those in South America. Geologic Range: Jurassic to Recent (Hasiotis and Demko, 1996; Hasiotis, 1997a, in press a). Trophic Classification: Ant nests represent multi-use structures that include reproduction, dwelling, gardening, and storage of waste materials and dead nest members. Nests are constructed; they are excavated and reinforced by pushing grains into place or by using feces or carton (masticated wood products mixed with saliva and other material). Environmental & Climatic Settings: The architecture of ant nests reflects not only substrate conditions necessary for nest construction, but also the amount of moisture, availability of plant and animal material (Wilson, 1971; Hasiotis and Bown, 1992; Holldobler and Wilson, 1990), and the trophic relation between ants and their community. Ant nests are typically found in the A and upper B horizons of soils in proximal to distal alluvial and marginal-lacustrine environments. The soil moisture regime represented by nests tend to be upper vadose zone to upper soil water zone (< 1 m below substrate). Deeper nests reflect lower soil moisture and water table levels, as well as ontogentically older nests. Nests in areas of high water table tend to be very shallow and are mainly in sediment piled-up at or above the surface. Surfaces of long-term exposure may contain multiple generations of cross-cutting ant nests. 4 cm chambers

galleries

Cross-sections of ant nests

4" diameter core

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ANT NESTS

B

A chambers

4 cm galleries

4 cm chambers

C

D

5 cm

galleries

4 cm

chambers

chambers galleries

E

F galleries

chambers

4 cm fungal garden

4 cm Ant nests: A) Cross-section of a relatively modern ant nest in a stabilized dune, Petrfied Forest National Park, Arizona. B) Cross-section of an ant nest, Miocene alluvial sandstone, Olson, Spain. C) Cross-section of stacked chambers of an ant nest, Miocene alluvial levee sandstone, Piraces, Spain. D) Cross-section of an ant nest, Miocene distributary channel–levee sandstone, Mequineza, Spain. E) Cross-section of a Miocene ant nest in pedogenically modified lacustrine limestone, Mequineza, Spain. F) Cross-section of a Miocene ant nest (circles) associated with rhizoliths in pedogenically modified lacustrine limestone, Fraga, Spain.

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ANT NESTS

A

B

1.5 cm 5 cm

C

D chamber

mm

ChamberS

GallerieS gallery

1.5 cm

Ant nests: A) Three-dimensional outcrop view and close-ups (B, D) of interconnected chambers and galleries of an ant nest in a highly-modified overbank splay sandstone, Brushy Basin Member, Jurassic Morrison Formation, Hanksville, Utah. C) Ant nest in core with sand-filled chambers and galleries in a dominantly siltstone matrix, Salt Wash Member, Jurassic Morrison Formation, Utah.

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ANT NESTS

A

B mm

mm

chamber chamber

gallery gallery

Ant nests in core showing different types of preservation: silty-mud filled (left) and sand-filled (right) chambers and galleries, Salt Wash Member, Upper Jurassic Morrison Formation, Utah.

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BEE CELLS AND NESTS - CELLIFORMA Description: Flasked- to capsule-shaped, lined cells with or without caps that are often spiral; cell walls are smooth and thin, composed of mud or very fine-grained materials. The cells occur as individuals in clusters associated in linear and circular patterns; some cell clusters share walls. The shafts and corridors leading to the cells of the nest are often not preserved. Cell diameter ranges from 0.3-1.0 cm and length ranges from 0.5-2 cm. Nests form T, L, or Ushapes located 10-200+ cm below the surface in sediment ranging from fine silts and clays to medium sand, or in fossil trees. In core, Celliforma commonly appears as thin-walled flask- to capsule-shaped cells or as various cross-sections through the structure. Interpretation: The various configurations of Celliforma represent the subterranean reproductive nests of bees (Hymenoptera: Apoidea). The cells contain food rations of pollen or other plant materials, and 100's of cells can make up a single nest. Nests with many attached cells in one or more configurations likely represent social behavior, whereas clusters of single cells and small clusters of shared-wall cells represent solitary to gregarious behavior. Geologic Range: Triassic to Recent (Hasiotis et. al, 1995; Hasiotis, 1997b, in press a). Trophic Classification: Nest and cells used for food-hoarding as a reproductive strategy. Environmental & Climatic Settings: The nest configurations of Celliforma are found in immature to mature soils (paleosols) constructed in proximal to distal alluvial and supralittoral lacustrine environments. They are also found in interdune deposits in semiarid and xeric settings. In terms of time, larger nests or clusters of solitary cells represent mature nests and nesting sites that are produced within a single season (year). Overlapping and crosscutting cells most likely represent multiple generations (multiple years) of reoccupation of a nest or nesting site. Climatically, extant bees construct nests in semiarid to hot-humid settings. Deeper nests reflect lower soil moisture and water table levels. When interpreted in conjunction with other ichnofossils and their tiering relation and the attributes of the paleosol they occur in, Celliforma is useful for interpretation of local hydrogeology and climate (seasonality and amount of precipitation), as described above, by constraining soil moisture levels. Enlargement of bee cell

cap tunnel Bee nest with completed cells

Cell wall

5 cm 1 cm

cell with closed tunnel newest cell

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bee nest with cells in 4" core

Cross-sections of bee cells and nests

BEE CELLS AND NESTS - CELLIFORMA

A

B

5 cm

C

D

1 cm 1 cm

E

cell wall

cell

F

cell

1 cm

cell wall

1 cm

Bee cells and nests: A) Cross-section and plan view (B) of a subterranean social bee nest showing an array of cells and main gallery system, Pleistocene coastal dune deposits, San Salvador Island, Bahamas. C) Side view of bee cells from a solitary bee nest, Celliforma isp., alluvial overbank deposits, Eocene Broken Arrow Formation, Montana. D) Note spiral closes of the cells in (C). E) Top view of the solitary bee nest, Uruguay auroranormae, showing cell cluster construction in an oxisol, lower Eocene Asencio Formation, Uruguay. F) Top view of the solitary bee nest, Uruguay isp., showing shared wall cell construction in a weakly modified proximal overbank deposits, Montior Butte Member, Upper Triassic Chinle Formation, Arizona.

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BEE CELLS AND NESTS - CELLIFORMA

B

A

cell cell wall

5 cm

C

D

mm

antechamber

cell cap cap cell

cell wall

mm

cell wall

Bee cells and nests: A) Cross-section view and close-up (B) of a subterranean social bee nest showing array of cells, Salt Wash Member, Upper Jurassic Morrison Formation, Burr Trail, Utah. C-D) Cross-section views of subterranean, solitary bee cells in core showing various morphologies of cells, Salt Wash Member, Upper Jurassic Morrison Formation, Utah.

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BEETLE TRACES - VERTICAL AND HORIZONTAL BURROWS, cf. PLANOLITES, ANCORICHNUS, AND MORE Introduction: Many kinds of beetles (Insecta: Coleoptera) inhabit environments that range from dry to wet where they construct burrows for long-term dwelling or short-term shelter, and for reproduction with minimal to presocial parental behavior. Burrows and nests exhibit a wide range of morphologies. Burrows can be horizontal (branched, unbranched, sinuous, straight), vertical (J- , Y-, and I-shaped and branched, unbranched), diagonal, and all variations in between. Nests can have a range of spheres, ovoids, and elipses associated with their structures. The morphology of beetle burrows and nests converge with those of bees, wasps, soil bugs, and earthworms. Beetle traces can be confused with the marine traces Thalassinoides, Ophiomorpha, Spongeliomorpha, Palaeophycus, and Conichnus. Simple open burrows constructed by beetles can be referred to Planolites. The next several pages are used to describe potential beetle trace fossils. Interpretation of Environmental Settings: Beetle burrows and nests are useful for interpreting ancient soil moisture and water table levels, rates of deposition, duration of subaerial exposure and soil formation, and ecological relationships with other organisms. 1) The predominance of horizontal burrows in small trough- and ripple-laminated to planarlaminated sandstones and siltstones (also associated with mudstones) suggests high water tables and standing water at or above the surface of the substrate. The greater the intensity of burrowing, the longer that particular interval remained undisturbed by deposition and erosion. 2) The predominance of vertical burrows in small trough- and ripple-laminated to planarlaminated sandstones and siltstones (also associated with mudstones) suggests water tables below the surface of the substrate. This also suggests that soil moisture levels were between 10-37%, the range which terrestrial and semiaquatic arthropods can tolerate for extended periods of time; this does not include conditions that result from extensive flooding or precipitation. The greater the intensity of bioturbation, the longer that interval remained undistrubed by deposition or erosion. Roots and other burrows may be associated with the beetle traces. 3) The deeper or longer the burrow or nest (in vertical aspect), the deeper the appropriate soil moisture levels are (between 10-37%) and the deeper the water table (in wet to semiarid climates). When associated with hydromorphic soils, the burrows and/or nests preserve the lowest levels to which the groundwater profile is supressed into the solum. The greater the intensity of bioturbation, the longer that interval remains undisturbed by deposition or erosion, undergoing a longer duration of pedogenesis. Roots and other burrows may be associated with the beetle traces. Geologic Range: Permian to Recent based on body fossils (Carpenter, 1992); ?Devonian to Recent based on ichnofossil evidence (Hasiotis et al., 1999). Trophic Classification: Beetle burrows and nests represent several different behaviors from simple to relatively complex. Simple vertical burrows can represent short-term shelters or long-term dwelling burrows. Nests with several openings and tunnels originating from a central shaft represent reproductive behavior of adults and the feeding and pupation (complete metamorphosis: larvae to pupa to adult) behavior of the larval beetles. In some instances, the larvae leave the cell after eating the original dung provisions and forage on fine roots and root hairs before they final reach the point of pupupation to the adult form (see also Adhesive Meniscate Burrows). In many cases, only the dung balls, ovoids, or cocoons are preserved and thus reflect a more complex history of behavior. 71

BEETLE TRACES - VERTICAL AND HORIZONTAL BURROWS, cf. PLANOLITES, ANCORICHNUS AND MORE Environmental & Climatic Settings: Beetle nests are constructed in soils developed in alluvial and marginal lacustrine environments that developed in arid to wet climates, but their traces are most prolific in semiarid to humid-moist lclimates. The are commonly found in the A and upper-part of the B horizons of soils and reflect the upper vadose zone of soil moisture (e.g., Hasiotis et al., 1993a; Vittum et al., 1999). In hydromorphic soils, the presence of burrows, nests, and balls reflects the drier part of the season when the soils are better drained. Beetles are abundant in areas with dung-producing vertebrates in grasslands or in their pre-Eocene equivalents. Beetle burrows and nests are most common in dry seasonal to wet seasonal (monsoonal) climates such as the Midwest and Rocky Mountain regions of the United States and the savannas of Africa. Below are specific examples of ichnotaxa and their diagnostic characteristics that represent various morphologies typical of various beetle behaviors. They are illustrated in the figures following this page. Description of traces possibly made by beetles: Ancorichnus--mainly horizontal to diagonal simple burrows filled with chevron-shaped menisci backfill (Frey et al., 1984). Two ichnospecies of this ichnotaxon are found in marine environments, whereas two others occur in continental environments. Because little is known about the overall occurrence of these ichnotaxa, the presence of this trace alone is not a reliable indicator of continental environments. Coprinisphaera--spherical and ovoid trace fossils composed of sandstone to siltstone that preserve the shape of dung beetle balls (Retallack, 1984; Genise and Bown, 1987). The balls are commonly the only portion of the nest preserved. The original nest contained at least one or more shafts with several openings to the surface. The shaft(s) led to 1) chambers that contained dung balls, 2) tunnels with small dung balls, or 3) cells with small dung provisions. Monesichnus--fusiform to ovate with or without an external groove that runs along the long axis of the trace fossil. The internal part of the nest is either empty or filled with menisci. Complex internal burrows are those constructed by a cleptoparasite (advantaceous insect that uses provisions/nests of other organisms) of the dung beetle (Genise and Laza, 1998). Scaphichnium--hook- to small J-shaped cells with a bulbous termination. Internally the trace is composed of alternating menisci originally composed of dung and vegetation (Hasiotis et al., 1993). These traces represent individual cells that are part of a nest similar in morphology to those of bees and wasps. The nest had a central shaft from which extended several tunnels that led to hook- to J-shaped cells which contained an egg laid by the female and provisions of dung and vegetation that filled the remaining space in the cell. Eatonichnus--small to large (7-15+ cm tall) fusiform to ovate structure composed of highly ornamented, closely compressed whorls that spiral around a central cavity. The filling of the cavity may be nondescript to meniscate. This trace fossil was tentatively thought to have been constructed by dung beetles (Bown et a., 1997). Smaller and larger well-preserved specimens, exhibit external and internal morphologies that suggest they were constructed by wasps rather than dung beetles (Hasiotis, 1997a). 72

BEETLE TRACES - VERTICAL AND HORIZONTAL BURROWS, cf. PLANOLITES, ANCORICHNUS AND MORE

1 cm

Terminal chambers

Larval tunnels

1 cm

Frass filled gallery

Adult tunnel

Beetle nests in wood--Paleoscolytus and Paleobuprestis

Adhesive meniscate burrows

shaft 3 cm

3 cm

Eatonichnus

Monesichnus 3 cm

tunnel cell with dung Dung

Scaphichnium

3 cm

shaft

Dung Beetle nest provisions

Coprinisphaera

dung ball

Beetle traces in 4" core 73

HORIZONTAL AND VERTICAL BURROWS - ?BEETLES Description: Horizontal to vertical burrows characterized as being passively filled or filled by active backfilling that results in menisci. These are thin (< 1mm) to thick (1-2 mm), and are packed either loosely or tightly with little space between the backfill. Burrows may or may not have a discrete wall bounding the menisci. Most of the generic horizontal and vertical burrows have distinct burrow walls. Most often these burrows have no specialized terminations, or the end is not clearly differentiated. If these types of traces weather in boas relief and expose alternating fine and coarse-grain sizes and weather, then refer to Scoyenia, Ancorichnus, and back-filled burrows. Burrows without a clear burrow wall are termed "adhesive" by Bown and Kraus (1983) because the backfill does not weather in boas relief or are not differentially weathered from the rest of the burrow (also see AMB page). Chambers are sometimes found within or at the end of the menisci trail, but most often the terminations are not visible. When chambers are present, they are defined by a distinct wall that may or may not be perforated by more meniscae. The chamber is commonly the same diameter as the trail, or may be slightly wider. The height of the chamber is usually 1 to 1.5 times the burrow width. The AMBs superficially resemble the marine trace fossils Taenidium and Muensteria. Interpretation: Passively filled, simple horizontal and vertical burrows, and burrows with menisci and related chambers are most characteristic of the behavior of ground beetles (Insecta: Coleoptera) and soil bugs (Insecta: Hemiptera). Passively filled horizontal and vertical burrows likely represent open burrows made by burrowing adult ground beetles or beetle larvae that construct burrows open to the surface for hunting. These burrows are similar in morphology to Skolithos and Planolites. The AMB traces likely represent the locomotion and feeding behavior of hemipteran and coleopteran larvae moving through the soil substrate. They would be feeding on roots and other organic debris (Willis and Roth, 1962; Villani et al., 1999). The chamber and its well-defined wall are likely due to the larvae compacting the walls by twisting motion of its body that compacts its feces and sediment. Some larvae will secrete a mucous that cements the compacted soil and feces prior to pupation (Villani et al., 1999). Geologic Range: Devonian to Recent (Hasiotis, 1997a; Hasiotis et al., 1999). Trophic Classification: Horizontal and vertical open burrows represent the dwelling, feeding, and shelter structures of various types of beetles and very few hemipterans (e.g., Stanley and Fagerstrom, 1974; Ratcliffe and Fagerstrom, 1980). Adhesive meniscate burrows represent foraging behavior of the larval stage in soil bugs (Insecta: Hemiptera) and beetles (Insecta: Coleoptera). The chamber(s) associated with a trail represents the transformation from larvae to adult (complete metamorphosis); several chambers in one trail may represent stages in prepupal molting. Environmental & Climatic Settings: The architecture of traces usually reflect 10-37% soil moisture that are typically found in A horizons and upperparts of immature soils. These traces are found in proximal to distal alluvial and marginal-lacustrine environments. Deeper burrows reflect lower soil moisture and water table levels in those substrates. Insects move up and down in the substrate to stay within appropriate moisture ranges. A food source (e.g., plant material) must be present in order for these organism to be present in the soil. Traces in areas of high water table tend to be very shallow. 74

BEETLE TRACES - BACKFILLED HORIZONTAL, VERTICAL BURROWS

A

B 5 cm

D

C

5 cm

5 cm

E

V V

H

F

H

H

V H

3 cm

Beetle traces: Outcrop cross-section (A) and plan-view (B) of vertical and horizontal burrows attributed to the burrowing of beetles. Both A-B with external morphology showing scratch patterns made during burrow excavation. C) Interior backfill of a horizontal burrow showing tightly packed meniscae that are not preserved through part of the burrow; similar to the burrow in (B). A-C from Oligo-Miocene alluvial to marginal lacustrine deposits Aragon Province, Spain. D) Plan-view of horizontal burrows with partial backfill patterns reflecting periods of feeding vs. locomotion, alluvial deposits, Church Rock Member, Upper Triassic Chinle Formation, Utah. E) Core cross-section of vertical (V) and horizontal (H) burrows that are passively filled, channel overbank splay deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Green River, Utah. F) Plan-view of horizontal burrows in outcrop showing cross-cutting pattern of individual burrows, overbank splay deposits, Mesa Redondo Member, Upper Triassic Chinle Formation, Arizona.

75

BEETLE TRACES - ANCORICHNUS

A

B

Beetle traces: A-B) Outcrop plan-views of burrows assigned to Ancorichnus isp. because of the chevronshaped and the distinct alternating coarse- and fine-grained backfilled meniscate pattern. The pattern suggests the cross of the legs by the organism while burrowing through the substrate while likely depositfeeding on organic debris. A) Overbank splay deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Arizona. B) Lacustrine deposits, Owl Rock Member, Upper Triassic Chinle Formation, Arizona.

76

BEETLE TRACES IN WOOD SUBSTRATES Description: Horizontal to vertical borings, in casts or permineralized trees, logs, roots, or stumps. Patterns often range from unorganized and irregular to highly complex and bilaterally symmetrical with radiating patterns from central tunnels. The diameter of the tunnels ranges from < 0.1 to >1.0 cm, and they may often begin with a very small diameter from the major tunnel and increase in diameter away from the tunnel. Tunnel patterns may be confined to small areas of the wood to patterns that girdle large areas of the tree. Larger, hollowed-out cavaties (w:l:h = 0.5 x 1.0 x 5 cm to > 5 x 10 x 400 cm) in the heartwood may also be the work of beetles that have eaten large sections of wood decomposed by fungal rot. Tunnels may or may not be filled with frass (a combination of chewed wood pulp and feces). Interpretation: The pattern represented by the horizontal, vertical, and radiating borings is most likely produced by wood-boring beetles (Insecta: Coleoptera). The traces represent the feeding and reproductive behavior of the adult and larval beetles. The adults construct a simple tunnel in which the female deposits her eggs into small grooves chewed into the tunnel wall. The irregular to highly complex radiating patterns of galleries are produced by the larvae that hatch from the eggs and eat their way through the wood. Terminal chambers at the ends of the tunnels represent the place where the larvae pupate into adults. These borings reflect the attack of a weakend tree while it was alive and upright. Larger cavaties in the heartwood are produced by fungal rot that are often eaten by adult and larval beetles, which occurs while the tree is standing or after it has fallen over. The larger cavaties usually occur in weakened trees and in the later life of trees. Geologic Range: Carboniferous to Recent (Scott, 1992; Hasiotis and Bown, 1992). Trophic Classification: The burrows represent the combined feeding (herbivory and saprivory) and reproductive behavior of adult and larval beetles (Insecta: Coleoptera). Environmental & Climatic Settings: Beetle borings in wood are often confused with borings of marine clams that belong to the ichnotaxon Teredolites isp. Beetle borings are often irregular in shape of the chamber and have long corridors that radiate away from a central shaft; Teredolites isp. does not have these features. This mistake is common with fossilized wood associated with marginal-marine and estuarine deposits. Paleoenvironments where trees grow range from levee to proximal and distal floodplains. Beetle borings in wood signify dry-seasonal to wet climates. Borings preserved in very poor condition or as part of crushed, indistinctive wood may represent logs that have been transported over a long distance. Pristine borings and wood-bark textures likely reflect little or no appreciable transport. 1 cm Terminal chambers

Larval tunnels

Frass filled gallery

Beetle nests in wood

Adult tunnel

In core, logs bored by beetles in terrestrial settings would have frass or sediment-filled galleries. The patterns are also distinctive of Teredolites and other marine borings 77

BEETLE TRACES AND WOOD SUBSTRATES

A

B

C

D 5 cm

Beetle traces in wood: A-B) Permineralized log with the beetle boring trace Paleoscolytus isp. showing typical radiating gallery pattern, Black Forest bed in the Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. C) Permineralized log with the beetle boring trace Paleobuprestus isp. with typical circular borings that penetrate vertically from the outside. Interior trace is similar to Paleoscolytus isp., Petrified Forest National Park, Arizona. D) Shrinkage cracks on the surface of a giant log buried as part of a channel deposit, upper-part of the Salt Wash Member, Upper Jurassic Morrison Formation, Shootaring Canyon, Utah. Shrinkage cracks and related features are often mistaken for trace fossils of boring insects.

78

DUNG BEETLE TRACES - COPRINISPHAERA, SCAPHICHNIUM Description: Burrow system composed of at least one shaft with several openings that lead downward to either serval large chambers or a series of smaller shafts. In the chamber are large spheres or ovoids of dung, sediment, and vegetation. Small ovoids and spheres of similar material are also found in more complex nests that resemble those constructed by bees, wasps, and ants. Diameter of shafts and tunnels ranges from 0.5 to > 2 cm. Spheres and ovoids range from 0.5 to > 5 cm in diameter. Most often only the spheres and ovoids are preserved in the rock record, though more recent (Neogene) continental deposits contain nearly complete nests. Interpretation: The pattern represented by this type of trace fossil is produced by dung beetles (Insecta: Coleoptera, Scarabiadae). These traces are constructed by the adult mating pairs of males and females for the specific purpose of rearing larval beetles, which feed on the dung and vegetative provisions. The female lays one or more eggs on the spheres and ovoids of dung. The eggs hatch into larvae which then feed on the dung. Some nest-forms represent little or no parental care, while others represent advanced parental care by staying with the larvae, protecting, feeding, and tending to them. They are constructed in immature to mature paleosols and also reflect the presence of dung-producing terrestrial and arboreal vertebrates. Geologic Range: Jurassic to Recent (Scott, 1992; Hasiotis, 1997a, 2000, in press a, b). Trophic Classification: The nests represent the reproductive behavior of adults (including food hoarding) and the feeding and pupation (complete metamorphosis: larvae to pupa to adult) behavior of the larval beetles (Insecta: Coleoptera). Environmental & Climatic Settings: Dung beetle nests are constructed in soils developed in alluvial and marginal lacustrine environments. They are commonly found in the A and upperpart of the B horizons of soils and reflect the upper vadose zone of soil moisture (Hasiotis et al. 1993a). In hydromorphic soils, the presents of nests and balls reflect the drier part of the season when the soils are better drained. Dung beetles are abundant in areas with dung producing vertebrates in grasslands or their pre-Eocene equivalents. Dung beetle nests are most common in dry seasonal to wet seasonal (monsoonal) climates such as the Midwest and Rocky Mountain regions of the United States, the savannas of Africa, and grasslands of South America. Dung

Dung Beetle nest

3 cm shaft

provisions tunnel cell with dung Scaphichnium

dung ball Coprinisphaera 4" diameter core

79

DUNG BEETLE TRACES - COPRINISPHAERA, S CAPHICHNIUM

A

B

5 cm

C

D

5 cm

F

E mm

mm

Dung Beetle traces: A-B) Outcrop cross-sections of dung beetle nests assigned to Coprinisphaera isp. showing main tunnel system of the adult beetles and the balls on which the female would have laid her egg(s), OligoMiocene alluvial and marginal lacustrine deposits, Piraces (A) and Mequineza (B) areas, Spain. C) Scaphichnium hamatum, a cell from part of a dung beetle nest, alluvial hydromorphic paleosols, lower Eocene Willwood Formation, Worland, Wyoming. D) Coprinisphaera isp. in alluvial channel-overbank deposits, upper Salt Wash Member, Upper Jurassic Morrison Formation, Fence Canyon, Utah. Note that the tunnels and shafts are not preserved. E-F) Cross-section of Coprinisphaera isp. in core with the defining character of the ball with or without destruction of the interior by the larvae, Salt Wash Member, Upper Jurassic Morrison Formation, Green River, Utah.

80

BEETLE TRACES - SCOYENIA Description: Horizontal to diagonal burrows charcterized by peristaltic widening and narrowing along the path of the burrow. The surficial morphology of the burrow walls exhibits overlapping pairs of fine-textured scratch marks on all 360 degrees of the wall, producing a ropey texture. Diameter of the burrows ranges from 0.2 to 1.5 cm. The burrows do not branch or exhibit multiple openings, however, different burrow paths may be reburrowed once an old tunnel is intersected. The burrow fill consists of thin, tightly packed backfill meniscae. Very commonly, a thin tube runs through the middle to lower part of the meniscae. Interpretation: The horizontal and diagonal sculptured burrows reflect the activity of beetle larvae (Insecta: Coleoptera). More recently this burrow morphology has been associated with the larvae of the dipteran family Tipulidae (Hasiotis, unpublished data). The trace fossil represents the foraging and deposit feeding behavior of a beetle or fly larva that uses peristaltic motion to move through the sediment. The presence of the thin tube cutting the laminae represents the fecal strand produced by the larvae. The thin remnent of the tube reflects the pushing motion of the body compacting the anus into the meniscae formed by the contraction and expansion of the body forward, pushing sediment backward. The absence of the tube is due to the lack of preservation of the anus and the different anal morphologies. The scratches are produced by protrusions from the larva's body that help it move through the sediment and protect the body proper from the sediment. These protrusions often are bifurcated at their tips, while others bifurcate at each bifurcation (Coleoptera and Tipulidae sections in Merritt and Cummins, 1978). Geologic Range: Permian to Recent (Hasiotis and Bown, 1992). Trophic Classification: The burrows are the combined feeding (herbivory and saprivory) and locomotion behavior of larval beetles (Insecta: Coleoptera) or craneflies (Insecta: Diptera). Environmental & Climatic Settings: Scoyenia was used by Seilacher (1967) to characterize his only defined continental ichnofacies. Hasiotis and Bown (1992), Hasiotis and Dubiel (1993), and Hasiotis (1997a) regard the Scoyenia ichnofacies as having limited utility because it is poorly defined and too broadly encompassing of all continental environments. Scoyenia occurs in fine-grained sandstone, siltstone, and mudstone in alluvial and lacustrine deposits. Recent work (Hasiotis and Bown, 1992; Hasiotis and Dubiel, 1993; and Hasiotis, 1997a) suggests that Scoyenia is an indicator of high soil moisture (close to 40%), high soil humidity (approaching 100%), and indurated substrates like those found in lacustrine environments. Climatically, occurs in wet seasonal (and wet monsoonal) to wet climates. Its occurrence in the wetter phases of dry seasonal climates deep within soils or in lake sediments distinguishes the wetter portion of the climate cycle or of the environment.

fecal strand

1 cm

view into meniscae

meniscae Scoyenia

Scoyenia in 4" core

81

BEETLE TRACES - SCOYENIA

A

B

mm

Scoyenia: A) Plan view of the trace fossil Scoyenia, from overbank alluvial deposits of the Permian Hermit Shale, Grand Canyon, Arizona. This trace is distinguished by its ropey outer texture that encompasses 360 degrees around the burrow wall. Interior of this trace is composed of closely spaced meniscae that often have a very thin central tube running down the middle through the meniscae. Without the presence of the outer texture and central tube, a burrow should not be related to this ichnotaxon. B) Close-up of Scoyenia, showing the ropey texture that is composed of pairs of overlapping scratch marks covering all of the burrow surface. Specimen from alfisols developed on alluvial overbank deposits, Petrified Forest Member of the Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona.

82

BEETLE TRACES - STEINICHNUS Description: Individual to networks of centimeter-sized cylindrical burrows predominantly horizontal that may or may not exhibit T- and Y-branching. The burrow walls contain deeply transversely striated walls and hemispherical uninflated to bulbous terminations. Differs from Thalassinoides in its lack of dichotomous branching and box-network burrow system of horizontal and vertical shafts and tunnels, and lack of large chambers and longitudinal scratches. Interpretation: The pattern represented by this type of trace fossil is produced by either mudloving beetles (Insecta: Coleoptera, Scarabiadae) or mole crickets (Orthoptera: Gryllotalipidae). These traces are constructed by the adult burrowing and pushing its way the through relatively firm, moist substrate just below the sediment surface. The scratches on the burrow walls are created by the burrowing mechanism: the organism excavating and moving sediment out of its path. Geologic Range: Triassic to Recent (Bromley and Asgaard, 1979; Hasiotis and Bown, 1992). Trophic Classification: These burrows represent the locomotion and, most likely, depositfeeding behavior of either mud-loving beetles (Insecta: Coleoptera, Scarabiadae) or mole crickets (Orthoptera: Gryllotalipidae). Environmental & Climatic Settings: Steinichnus is comonly constructed in wet habitats associated with alluvial and marginal lacustrine environments. They are mainly found in sediment along river banks, back-swamps and splays, and pond or lake shorelines (e.g., Hasiotis et al., in review). These burrows signify areas of high water tables or standing water that is relatively fresh. Like today, the makers of Steinichnus are most common in perennial bodies of water or temporary bodies of water associated with wet seasonal to wet climates with high humidity. These burrows could also be found in dry seasonal climates that have permanent rivers or lakes associated with them.

1 cm

burrow wall scratches underside of burrow 4" diameter core

83

BEETLE TRACES - STEINICHNUS

A

B 5 cm

C

D

1 cm

5 cm

Steinichnus burrows: A) Plan-view of the bottom of a horizontal burrow, Steinichnus isp., from distributary channel and overbank sandstones, Upper Eocene Uinta Formation, Myton, Utah. Note the crossing scratch patterns that most likely resulted from the burrowing legs of the beetle. B) Outcrop plan-view of the bottom of Steinichnus that exhibits the relationship between the burrow and the surface from which it originated. The burrow is just below the substrate-water-atmosphere interface. C) Another Steinichnus isp. showing a slightly different scratch pattern on the bottom side of the burrow. The scratches are more parallel to the direction of burrow. cell from part of a dung beetle nest, alluvial hydromorphic paleosols, Lower Eocene Willwood Formation, Worland, Wyoming. B-C) Burrows from alluvial overbank splay deposits, Salt Wash Member, Upper Jurassic Morison Formation, Shootaring Canyon, Utah. D) Modern burrow of the mud-loving beetle (Coleoptera: Heteroceridae) constructed along the banks of the Green River, Dinosaur National Monument, Utah. The interior of the burrow is similar to the architectural and surficial burrow morphology of Steinichnus isp.

84

BRACKISH WATER TRACE FOSSIL INDICATORS Description: Brackish water environments are characterized by a suite of ichnofossils that have been described in detail by Pemberton and others (e.g., Pemberton, 1992). The plate associated with this sheet are just a few examples of trace fossils produced by marine to brackish water organisms that are indicative of estuarine to tidal environments, as well as highly stressed environments like hypersaline lagoons, bays, and salt flats. These types of traces include Teichichnus, Arenicolites, Palaeophycus, Planolites, Haplotichnus, Conichnus, Gyrolithes, Rosselia, Skolithos, and Bergaueria. Interpretation: These traces typically occur in high abundances and very low diversity, which ranges from 1 to 3 different types. They are associated with sedimentary structures that reflect tidal, estuarine, and hypersaline depositional environments. The tops of individual beds are bioturbated, and are interbedded with nonbioturbated intervals. They are common in environments that experience extreme fluctuations in energy levels, sediment type, and water salinity. Geologic Range: Ordovician to Recent (Pemberton, 1992 and refences therein). Trophic Classification: The trace fossils listed above fall into suspension feeding, depositfeeding, and dwelling burrows. Environmental & Climatic Settings: For details of the characteristics for environments of deposition, consult the trace fossil volumes of Pemberton and papers by Pemberton and others (1992 and references therein). In general, transitional environments like the intertidal zone, shallow lagoons and bays, estuarines, and deltas of various configuration have salinity gradients that vary from steep to gentle. The variables that control the salintiy gradient include: the amount of freshwater input, rainfall, evaporation, tidal range, coastline morphology, and wind direction and velocity. These variables combine to produce environments that are physiologically stressful to organisms. Brackish water environments occur in many climates, and thus, are not good indicators of any particular climatic setting.

85

Brackish water indicators: A) Polychaete worm burrows in a spiral pattern, walls with scratches, Delmonte Mine, Tidwell Member, Upper Jurassic Salt Wash Formation, Ticaboo, Utah. B) Burrows of small clams, Lockeia (crescent-shaped), with paired tubes of Arenicolites, Windy Hill Member, Upper Jurassic Salt Wash Formation, Dinosaur National Monument, Utah. C) Rasping traces of a surface feeding organism, most likely a large gastropod. D) Surface trail Haplotichnus isp. Produced by a small gastropod, Windy Hill Member, Upper Jurassic Salt Wash Formation, Dinosaur National Monument, Utah. E) Opening of Conichnus isp. With many paired tubes of Arenicolites, Windy Hill Member, Upper Jurassic Salt Wash Formation, Dinosaur National Monument, Utah. F) Palaeophycus and Planolites, Windy Hill Member, Upper Jurassic Salt Wash Formation, Dinosaur National Monument, Utah.

86

CADDISFLY CASES-TEKTONARGUS Description: The architecture is distinct and reflects the nature of the material used to construct the case, from sand grains and leaf fragments to the shells of small snails. The case architecture is cylindrical tubiform to coiled and spherical. The cases range in length from about 1-2 cm and from 0.4-0.8 cm in diameter. Typically one or both ends are open. They often occur in great abundance within small areas. Interpretation: These traces are produced by larvae of caddisflies, which are holometabolous insects with slender moth-like adults that are most common around streams, ponds, rivers, and lakes. The larvae of modern caddisflies are herbiverous or carnivorous, and they are either freeliving, net-spinning, or construct saddle cases. Larvae of various instars construct cases for camouflage and shelter from predation. The cases can either be stationary or can be moved about by dragging (Merritt and Cummins, 1996; Hasiotis et al., 1998). Geologic Range: Triassic to Recent (Donovan, 1994; Hasiotis et al., 1994, 1998). Trophic Classification: These traces are used for dwelling and feeding by the larvae of caddisflies. Environmental & Climatic Settings: These traces are found in aquatic portions of alluvial and lacustrine environments, particularly in channels, floodplain ponds, and the shallow littoral zones of lakes with ample vegetation. They are very rare in wet terrestrial environments adjacent to lakes and rivers. They are indicators of freshwater aquatic environments with a perennial source of water. There traces are evidence that the water table has intersected the ground and is above the land surface. Climatically, caddisflies are found in the temperate and tropical zones, and are less abundant in colder climates.

saddle case 1 cm

straight case

4" diameter core

87

CADDISFLY CASES-TEKTONARGUS

A

B

C

D

Caddisfly traces-Tecktonargus: A) Caddisfly case showing the construction by granules, encased in mudstone deposited in a floodplain pond, Brushy Basin Member, Upper Jurassic Morrison Formation, Fruita, Colorado. B) Partial caddisfly case showing the hollow internal portion where the caddisfly lived (arrows), Brushy Basin Member, Upper Jurassic Morrison Formation, Fruita, Colorado. C) Closed end of the case and raised ring around the case suggesting that the case was washed in and settled into the soft mud substrate and produced a raised rim on impact, Brushy Basin Member, Upper Jurassic Morrison Formation, Fruita, Colorado. D) Caddisfly cases in finegrained sandstones of alluvial levee deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petritifed Forest National Park, Arizona.

88

CRAYFISH BURROWS - CAMBORYGMA Description: Subvertical to subhorizontal shafts exhibiting a range of complexity of branching patterns and chamber formation. Lateral to downward branches (corridors) and chambers of various size, shape, and location within the burrow system. Diameters range from about 1-14 cm and exhibit depths of 10-400+ cm; length is variable depending upon complexity of the burrow architecture. Burrow walls exhibit a combination of surficial features that include scratch marks (mm-scale; length = cms), scrape marks (cm-scale; length = cms), striations (mm-scale; length = cms), knobby-hummocky texture (mm-cm scale; length = mm-cm), and mud- and pebble-linings (mm-cm scale-length = cms). Towers are sometimes preserved at the burrow entrances. Interpretation: The architectural and surficial burrow morphologies reflect burrowing by crayfish (Hasiotis, 1993a, b; Hasiotis and Mitchell, 1993). Today, crayfish occur naturally on every continent except for Africa and Antarctica. One ichnotaxon and four ichnospecies are used to designate crayfish burrows in the geologic record: Camborygma symplokonomos, C. araioklados, C. litomonos, and C. eumekenomos. The surficial burrow morphology reflects the burrowing mechanism used by the crayfish: (1) scratch marks are made by the tail; (2) scrape marks are made by the claws, (3) striations are made by the swimmlettes below the abdomen, (4) knobby-hummocky textures are created by the walking legs, and (5) mud- and pebblelinings are made by the crayfish packing parts of the burrow wall with fine-grained and pebblesized material. Geologic Range: Permian to Recent (Hasiotis and Mitchell, 1993; Hasiotis 1997a, 1999). Trophic Classification: Crayfish burrows are structures used for dwelling and reproducing. The crayfish are omnivores. They feed on vegetation from outside the burrow, as well as material and organisms that fall or venture into their burrows. Environmental & Climatic Settings: These traces, found in weakly- to well-developed paleosols, formed in proximal to distal alluvial and marginal-lacustrine environments. The uppermost part of the burrow horizon represents discontinuity surfaces of variable duration time. The depth and architecture of crayfish burrows reflect the depth and fluctuation of the water table, and soil moisture conditions. The deepest branching part or the largest chamber marks the position of the water table. The distribution of the burrows reflects the local to regional paleohydrologic regime of the environment. In turn, water table depth, soil moisture levels, and other related factors are controlled by the local and regional climatic setting. Great abundances of crayfish burrows occur in humid to hot, wet seasonal climates. They are rare in semiarid climates.

1m

chamber

A A

A

chimney

B vadose zone

C. symplokonomos

wa

te

Camborygma litomomos

ab

le

Cross-section of crayfish burrows phreatic zone through a channel-overbank environment kms

chamber

shaft

rt

B

B C. eumekenomos

Crayfish burrow in 4" core

89

90

CRAYFISH BURROWS - CAMBORYGMA

A

B

mm 10 cm

C

D 29 cm

F

E

25 cm

25 cm Crayfish burrows: A) Outcrop cross-section of Camborygma eumekenomos in a mature paleosol developed in alluvial overbank deposits, red siltsone member, Triassic Chinle Formation, Eagle Basin, Colorado. B) Core crosssection of Camborygma litonomos in channel sandstone, Salt Wash Member, Jurassic Morrison Formation, Utah. C) Outcrop section of Camborygma eumekenomos in a well-developed paleosol in alluvial deposits, Shinramp (Mottled Strata) Member, Triassic Chinle Formation, Professor Valley, Utah. D) Outcrop cross-section of Camborygma eumekenomos in a mature paleosol developed on the Middle Triassic Moenkopi Formation, Petrified Forest National Park, Arizona. Paleosol is Late Triassic in age. E–F) Outcrop section of Camborygma eumekenomos in a well-developed hydromorphic paleosol; arrows in (E) shows where burrows become horizontal and (F) shows the churned substrate due to hundreds of generations of crayfish burrowing; Upper Paleocene alluvial deposits, Fort Union Formation, Washakie Basin, Wyoming.

91

DINOTURBATION, TRACKS, AND TRACKWAYS Description: Well-definded to poorly formed impressions, shallow to deep. Best tracks exhibit outline of toes (with or without nails) and heel. Poorly formed to highly deformed tracks appear as circular to oval load casts. Sides of traces with or without scratches that run parallel to the length of the track. Impressions of toes or heel may or may not be present. These traces occur as individual tracks, multiple and aligned trackways, and as multiple distinct to overlaping depressions in various states of preservation. Interpretation: The difference in the preservation of tracks, trackways, and dinoturbation reflects the moisture and consistancy conditions of the substrate. In core, these traces are difficult to recognize, however, several elements can be identified. Portions of imprints of toes, digits, and heels have been interpreted in core, and resemble part of tracks seen in outcrop. These features take up part of or all of the cross-sectional area of a core. Also associated with the tracks are contorted bedding produced from the animal in loose substrates. The size and shape of the tracks represent different types of dinosaurs that constructed them. Sauropod tracks: among the most common as dinoturbation; oval to circular and range in diameter from 40-100+ cm; five toes preserved maximum; front tracks oval and smaller than rear tracks. Theropod tracks: three-toed with angles of 20-90 degrees between the toes; range in diameter from 10-50 cm. Ornithopod tracks: large and small sizes, from 10-30 cm, and difficult to identify accurately. If substrates are firm and lack high levels of moisture, then no impressions or only shallow tracks will be produced. If substrates contain high levels of moisture, then deep, poorly formed tracks will be produced. When many animals are traveling over the same surface that is high in moisture, a trampled ground will form that contains multiple, poorly formed footprints that resemble large and ubiquitous load casts. Geologic Range: Triassic to Cretaceous (Gillette and Lockley, 1989; Gillette, 1999). The amount of dinoturbation increases in the Mesozoic with the increase in size and diversity of the Dinosauria; dinoturbation tapers off close to the end of the Cretaceous due to the extinction of the dinosaurs. Trophic Classification: These organisms represent the presence of herbivores, omnivores, and carnivores. The larger the number of footprints, the larger the number of organisms that were present in that area; one individual does not tend to trample an area. Environmental & Climatic Settings: These traces are found in proximal to distal alluvial, supra- and epilittoral lacustrine, and transitional environments assoicated with estuarine and tidal settings. A large amount of dinoturbation reflects a period of high water tables at or above the paleosurface, and is proportional to the overall amount of water in the system: high degree in wetter climates, lowest degree of dinoturbation in dry climates. paleosurface

well-formed

toe impression deep, well formed

highly deformed

20 cm

Cross-sections of dinosaur tracks 4" diameter core

92

DINOSAUR FOOTPRINTS AND DINOTURBATION

A

B 5 cm

5 cm

C

5 cm

D

E 1.5 m

Dinoturbation: A) Outcrop cross-section of a dinosaur footprint in overbank deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Naturita, Colorado. B) Outcrop plan-view of several dinosaur trackways in channel margin deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Fence Canyon, Utah. C) Individual three toed dinosaur footprint in outcrop plan-view, Moab Tongue of the Middle Jurassic Entrada Sandstone, Moab, Utah. D) Outcrop cross-section view of channel and overbank sandstones, siltstones and mudstones containing several trampled zones (arrows) in the channel margin and in overbank deposits, Salt Wash Member, Upper Jurassic Morison Formation, Naturita, Colorado. E) Outcrop cross-section view of dinosaur footprints (arrows) with channel sandstones, deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Naturita, Colorado.

93

DIPTERAN CASES AND COCOONS Description: Predominantly horizontal tubes that are irregular, linear, to slightly U-shaped. Tubes range in length from 0.7-2.0 cm and range in diameter from 0.1-0.3 cm. Some specimens preserve a surficial morphology of irregular to grainy texture that reflect the material used to build the tube, which includes silt, sand grains, and organic debris. When compressed, the tube is flattened and openings are nondistinct. The tubes occur in great abundance within a very small area, typically 100 individuals per 10 cm2, and are found in these small patches associated with one another. Also found with or without these tubes are spherical traces that are pellet-shaped, typically visible in outcrop as hemispheres, 0.1-0.3 cm in diameter. They are, however, most abundant with a diameter of a mean of 0.15 cm. The surficial morphology of the spheres are irregular and take on the appearence of the sediment that they are preserved in. Interpretation: These structures are the cases and cocoons of dipteran larvae (Insecta: Diptera). The eggs where laid in the water by terrestrial females and larvae spend their part of the reproductive phase as aquatic organisms. The cases are built around the body for protection and concealment from predators. The spherical cocoons represent the aestivation phase of the larvae during which time it will wait for the return of water to where it was hatched. Geologic Range: Triassic to Recent (e.g., Hasiotis et al., 1994; Hasiotis, 1997a). Trophic Classification: The tubes are dwelling structures used by the fly larvae who feed as shredders of leaf and other plant litter; the cocoons represent the dormant stage. Environmental & Climatic Settings: These insects construct their tubes once they hatch and grow as larvae, part of the complete metamorphosis cycle in holometabolous insects. They are typically found in environments with ample water, such as proximal alluvial, palustrine, lacustrine environments. They are also found in wet interdune and coastal wet interdune environments. Some species can also tolerate short periods with no water in their habitat, such as ephemeral floodplain ponds and swamps. Today, the Diptera are found in nearly all climatic zones on Earth, and as polerward as the most distant islands of Anarctica, North America, and Eurasia. In all, most larvae require a regularly seasonal water body to complete the life cycle to adult stage.

1 cm

Uncrushed and crushed tubes

94

4" diameter core

DIPTERAN CASES AND COCOONS

A

C

B

3 cm

2 cm

2 cm

D

5 cm Dipteran cases and cocoons: A) Recent dipteran cases in an ephemeral floodplain pond, upstate New York. B) Dipteran cases in standing water deposits associated with overbank-crevasse-splay deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. C) Dipteran cases (tubes) and cocoons (small spheres) in standing water deposits associated with overbank and crevasse-splay deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. D) Dipteran cocoons (small spheres) in standing water deposits associated with overbank and crevasse-splay deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona.

95

EARTHWORM TRACES-EDAPHICHNIUM Description: Vertical to horizontal tubes 0.3-5+ cm in diameter, but more commonly 0.32 cm in diameter. Observable burrow lengths vary between 1-10+ cm in outcrop and core. Surficial morphology is typically bulbous, pustulose, to smooth, and often with individual pellets preserved, making the burrow wall irregular. Similar in appearence to Ophiomorpha, but differing in that the whole volume of the burrow is completely composed of pellets, and the burrow wall is highly irregular; the pellets also are variable and size and morphology. Interpretation: These structures are the burrows and burrow fills of earthworms (Annelida: Lumbricacea). The pellets are the faeces of the earthworms, which are typically composed of inorganic and organic soil matter that sometimes contain high amounts of calcium carbonate. The variation in burrow size reflects different sizes and, mostly likely, different species of earthworm. The burrow morphology variation reflects the amount of moisture in, and that passes through, the subsurface during and after it is made. Geologic Range: Triassic to Recent (e.g., Bown and Kraus, 1983; Hasiotis et al., 1994). Trophic Classification: The burrows represent the feeding and dwelling structures of earthworms that are used mostly for detritivory of plant litter and of organic soil matter. Environmental & Climatic Settings: These organisms typically live in alluvial, palustrine, and marginal-lacustrine environments. They are air-breathers so they must be above the water table, but they must also have enough moisture to keep their soft bodies from drying out. Some species can tolerate short intervals of drier conditions--some will burrow deeper into the substrate, while others will lie dormant. In general, these traces are good indicators moderate to highly fluctuating soil moisture levels. They most commonly occur in A-B soil horizons with varying degrees of organic matter within them. Today, the largest earthworms are found in Australia in tropical climates that receive ample amounts of precipitation, and the soils have relatively high organic content.

earthworm burrow

pellet 2 cm

96

4" diameter core

EARTHWORM TRACES-EDAPHICHNIUM

A

B 5 cm

5 cm

C

D

1 cm 1 cm Earthworm traces-Edaphichnium: A) Edaphichnium preferentially preserved by carbonate in a calcic alfisol, Oligo-Miocene alluvial deposits, Olson, Spain. B) Very large Edaphichnium preserved by carbonate in inceptisols developed on proximal overbank deposits, Lower Eocene Willwood Formation, Wyoming. C) Core cross-section of traces interpreted as pellets in Edaphichnim, preferentially preserved by carbonate, Salt Wash Member, Upper Jurassic Morrison Formation, Green River, Utah. D) Core cross-section of traces interpreted as pellets in Edaphichnim, preferentially preserved by carbonate, Salt Wash Member, Upper Jurassic Morrison Formation, Green River, Utah.

97

EARTHWORM TRACES-EDAPHICHNIUM

A

B

Earthworm Traces--Edaphichnium: A) Core photography and drawing (B) of Edaphichnium and pelletal construction (fecal pellets) in overbank levee deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Shitamaring Canyon, Ticaboo, Utah.

98

FLYING TRACES Description: Curvilinear thin, shallow trails with multiple, self-crossing loops of varying roundness, height, and width. The number of loops and degree of cross-over is highly variable and irregular. They do not usually occur in great abundance and are relatively rare. These trails differ from Haplotichnus and Cochlichnus in that flying trails are very smooth and shallow. Interpretation: These traces were produced by flying insects, such as moths and butterflies (Lepidoptera), bees and wasps (Hymenoptera), damselflies and dragonflies (Odonata), and a host of flies (Diptera). Due to some unforeseen event, like landing on or being blown on to a wet and sticky surface, a flying insect becomes trapped and tries to fly free. While the insect is applying torque to break free, it makes several circular maneuvers. This pattern, coupled with flying in a "straight" direction, results in a thin shallow trail with several to many circular to elliptical over-crossing loops. Insects most likely to produce such trails are those with elongate abdomens, whip-like tail extensions, and large wings that tend to be a hazard in high gusts of wind or can become ladened with moisture. Geologic Range: Carboniferous to Recent (e.g., Hasiotis et al., 1994; Hasiotis, 1997a). These traces most likely can be found as early as the earliest record of flying insects. Trophic Classification: These traces represent escape behavior of flying insects. Environmental & Climatic Settings: These traces are found in marginal-marine and continental environments associated with shallow water. When they do occur they are particularly noticable in marginal-channel, levee, and crevasse-splay environments. These traces also occur in marginal-lacustrine environments. They are indicators of exposure surfaces at the sediment-water-air interface in subaqueous to semiaquatic environments, and they also exhibit firm to soft, but sticky substrates. Climatically, these traces can be found where flying insects live, ranging from cold polar to wet tropical to hot arid climates with intermittant rainfall. Nevertheless, these loop-to-loop traces will occur more frequently in wetter and warmer climates where the diversity and abundance of insects is higher.

10 cm

4" diameter core

99

FLYING TRACES

A

B

Flying traces: A-B) Plan view of the multiple looping surface trails interpreted as the trace of a flying insect that was caught on a surface with a thin film of mud and water, proximal alluvial overbank deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona.

100

FRESHWATER CLAM TRACES Description: Medium to large almond- to egg-shaped traces that taper to sharp and obtuse points at either end. This shape is associated with horizontal to quasi-horizontal and vertical backfill menisci to homogenous-filled trails behind them. This pattern also occurs in verticallyoriented, downward deflected menisci terminating in upward deflected egg-shapes that do not leave behind distinct burrow walls. These traces differ from Lockeia in size and shape, and Pelecypodichnus does not exhibit cheveron-shaped meniscae composing trails. Interpretation: These traces are produced by freshwater clams (Bivalvia: Unionidae) that are most common in streams, ponds, rivers, and freshwater lakes. The shape reflects the morphology of the clam, while the associated patterns reflect distinct behaviors. Horizontal trails are produced by the locomotion of the clam through the substrate. The almond-shape reflects resting and suspension feeding traces. The vertical pattern without distinct burrow walls reflects escape behavior due to rapid sedimentation (e.g., Hantzschel, 1975; Hasiotis, in press b). Some workers have synonimized Pelecypodichnus with Lockeia (e.g., Pemberton et al., 1992), but there is enough morphologic and behavioral differences to warrant the separation of the forms. Geologic Range: Triassic to Recent (Hantzschel, 1975; Hasiotis and Bown, 1992). Trophic Classification: These traces represent resting, suspension fedding, locomotion, and escape behavior in freshwater clams. Environmental & Climatic Settings: Freshwater clam traces are found in aquatic portions of alluvial and lacustrine environments, particularly in channels, floodplain ponds, and the shallow littoral to sublittoral zones of freshwater lakes. They form in quite water settings, as well as in flowing water environments; these clams do not live in stagnant or low-oxygen water. They are indicators of perennial freshwater aquatic environments. Their traces are evidence that the water table is above the land surface. Climatically, freshwater clams are found in the temperate and tropical zones, and also occur in regions of colder climates.

plan view

2 cm cross-section iew

plan view

4" diameter core

5 cm

101

FRESHWATER CLAM TRACES – PELECYPODICHNUS

A

(R)

B 5 cm

(L)

5 cm

D

C

5 cm

E

5 cm

F 5 cm

5 cm

Freshwater Clam Traces - Pelecypodichnus: A) Resting (R) and locomotion (L) traces of freshwater clams in littoral lacustrine, interdistributary channel sandstones, Tidwell Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. B) Resting traces of freshwater clams in channel sandstones, Brushy Basin Member, Upper Jurassic Morrison Formation, Cleveland-Lloyd Quarry, Utah. C) Locomotion traces of freshwater clams in channel sandstones, Salt Wash Member, Upper Jurassic Morrison Formation, Blue Mesa, Colorado. D) Restingtraces of freshwater clams in channel sandstones, Salt Wash Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. E-F) Escape traces (and close-up) of freshwater clams produced by a community of densely packed packed clams in chanel sandstones, Tidwell Member, Upper Jurassic Morrison Formation, Hatt Ranch, Utah.

102

FRESHWATER CLAM TRACES

A

B

C

D

E

F

Freshwater Clam Traces – Pelecypodichnus: A-B) Resting traces (and close-up) of a community of freshwater clams in channel sandstones, Brushy Basin Member, Upper Jurassic Morrison Formation, ClevelandLloyd Quarry, Utah. C) Resting traces of freshwater clams in channel sandstones, Salt Wash Member, Upper Jurassic Morrison Formation, Colorado National Monument, Colorado. D) Resting traces of freshwater clams in lacustrine littoral sandstones, lower part of the Upper Jurassic Morrison Formation, Gibson Reservoir, Montana. E-F) Resting traces produced by a dispersed community of clams in channel and chute-channel sandstones, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. The scale in the photographs is 5 cm.

103

HORSESHOE CRAB TRACES-KOUPHICHNIUM Description: These traces occur as several types of morphologies. Heteropodous tracks of great variety with either 2 chevron-like series of 4 oval or round holes or bifid V-shaped impressions or scratches that are forwardly directed. Tracks are also as one pair of digitate, flabellar, or similarly shaped birdfoot-like imprints with/without median drag-marks. These tracks can be traced into a series of cresentic-shaped impressions associated with mixed or jumbled sediment. These traces range in width from 5-15 cm, and can be traced for up to 10 m along bedding plane surfaces. These trails also occur as composite and overlapping patterns associated with specific behaviors. Interpretation: These traces were produced by horseshoe crabs (Arthropoda: Chelicerata), and include several specific behaviors. Pairs of bifid or digitate impressions with/without tail drags are crawling trails. Lunate impressions represent feeding behavior. Cresentic impressions associated with the nearly complete to complete body impression represent resting or hiding behavior. Composite trails are mating behavior climaxing in a nuptial embrace where the two trails become one. Overall, the shape and depth of these traces are a function of substrate consistency. Geologic Range: Devonian to Recent (e.g., Hantzschel, 1975; Hasiotis and Demko, 1996). Trophic Classification: These traces represent locomotion, feeding (detritivory), protection (hiding), and reproductive behavior. Environmental & Climatic Settings: These traces are found in both marine and continental environments; horseshoe crabs have been extinct in continental settings since the end of the Jurassic. Other than marine settings, horseshoe crab traces also occur in channel, levee, and crevasse-splay environments, and in shallow, marginal-lacustrine environments. They are indicators of shallow, subaqueous to semiaquatic environments with relatively firm substrates. These traces, today as in the geologic past, are most often found in tropical to cool temperate climates; the cooler end of the spectrum is, associated with warm ocean currents from the tropics and substropics. Ancient horseshoe crab traces, including those in continental environments are associated with tropical climates.

10 cm

horseshoe crab traces arrows = direction of travel

104

4" diameter core

HORSESHOE CRAB TRACES - KOUPICHNIUM

A

B

C

D

5 cm

5 cm

3.5 cm

E

H

5 cm

F

H

5 cm

Horseshoe crab traces: A) Crawling trail of a horseshoe crab in levee deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. B-C) Depositfeeding trail of horse-shoe crab in levee deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. D) Composite crawling trail of horseshoe crabs in levee deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona; note-this behavior is associated with mating where the male follows the female, which ends in a “nuptial embrace”. E-F) Horseshoe crab resting or hiding trace, interpreted by the deeper impressions of the head or cephalic region (H), Tidwell Member, Upper Jurassic Morrison Formation, Colorado National Monument, Colorado.

105

INSECT LARVAE BURROWS-FUERSICHNUS Description: Shallow vertical to horizontal U-tube(s) 0.3-1.0 cm in diameter and 0.1-2.0 cm in depth. The construction of this burrow-type is based on a repetition of a vertical or horizontal tube. Vertical tubes generally follow the same path without increasing its depth, but movement sideways is sometimes visible. Horizontal tubes are added with movement to form a pattern of nested, broad U's from the outside inward [((((((((]. The surficial burrow morphology is typically bulbous, pustulose, to smooth walls. These traces differ from Rhizocorallium in that there is no external tube and spreitae between them. Rarely is an external tube formed, and if present, it is usually defined on one side of the pattern. Interpretation: These burrows were constructed by deposit-feeding insect larvae that most likely belong to mayflies (Insecta: Ephemeroptera). The U-tubes are given different names based on their position in the sediment. Horizontal burrows are referred to as Fuersichnus communis, while vertical tubes are referred to as F. singularis (e.g., Bromley and Asgaard, 1979; Ekdale et al., 1984). The burrows are constructed by the larvae as it changes position in the sediment. Geologic Range: Triassic to Recent (e.g., Bromley and Asgaard, 1979; Ekdale et al., 1984; Hasiotis et al., 1994). The fossil record of mayflies extends to the Carboniferous (Carpenter, 1992). Trophic Classification: The horizontal burrows represent deposit-feeding and dwelling burrows, while vertical burrows represent suspension and dwelling burrows. In general these organisms are detrivores. Environmental & Climatic Settings: These burrows are commonly found where water is present in alluvial, palustrine, and shallow lacustrine environments. They are aquatic larvae of flying insects, mayflies, that have a complete metamorphsis cycle. The larvae are fully aquatic and need oxygenated water. Climatically, the constructors of these burrows presently occur in tropical to cool temperate climates. Geologically, these burrows have been found in tropical to subtropical climatic settings. They are indicators of aquatic perennial to ephemeral environments; ephemeral conditions typical of floodplain ponds and palustrine settings where temporary water bodies are common for parts of the year.

Top view horizontal Fuersichnus communis

Side view vertical

F. singularis

4 cm 106

4" diameter core

INSECT LARVAE BURROWS - FUERSICHNUS

A

B

C

D

3 cm

F

5 cm

E

5 cm Fuersichnus isp.: A) Fuersichnus singularis preserved in shallow water lacustrine deposits, Owl Rock Member, Upper Triassic Chinle Formation, Bedrock, Colorado. B) Close-up of Fuersichnus singularis showing evidence of multiple passes through the shallow U-tubes and its irregular surface, Owl Rock Member, Upper Triassic Chinle Formation, Bedrock, Colorado. C) Fuersichnus communis preserved in shallow freshwater lacustrine deposits, Tidwell Member, Upper Jurassic Morrison Formation, Delmonte Mine, Utah; similar to Phycodes isp., a marine deposit-feeding trace. D-F) Fuersichnus communis preserved in shallow water lacustrine deposits, Tidwell Member, Upper Jurassic Morrison Formation, Atkinson Mesa, Colorado. Series of pictures shows the variation in morphology of this ichnofossil.

107

ROOT TRACES-RHIZOLITHS Description: Filamentous to tubular structures that range in diameter from 0.1-100+ cm. They commonly taper downwards and exhibit downward and lateral branching of smaller diameter that also taper along their lengths. Tubular structures may also have filamentous traces associated along their outer walls and at their terminations. Filamentous traces exhibit patterns that are fractal. Overall depths (length = > depth) ranges from 1-100+ cm; rarely do they range between 500-10000 cm. Interpretation: The architectural and surficial morphologies of these traces reflect patterns produced by ground plants and trees with roots or rooting structures. Major types of root patterns include shallow (adventitious) roots, buttressed trunks, tap roots (with secondary branching), prop (stilt) roots, neumatophores (breathing tubes) and clinging roots of vines (Pfefferkorn and Fuchs, 1991). Types of preservation include cellular structure (petrifications), coaly films, molds and casts (steinkerns), drab haloes, rhizocretions, deflections of bedding planes, and brecciations and tepee structures in carbonate (Klappa, 1981; Retallack, 1990; Pfefferkorn and Fuchs, 1991). Roots and rooting structures of plants are true trace fossils in that they preserve the behavior of the plant with respect to the substrate conditions. Roots live and die, move upward and downward depending on the soil moisture and water table levels, and grow through and around obstructions and hard layers in the subsurface. Geologic Range: Ordovician to Recent (Hasiotis, 1997a; Retallack, 1990; Hasiotis et al., 1999). Trophic Classification: Roots are used to obtain moisture and nutrients from the substrate. They are also used for upright support of the plant and are modified according the character of the substrate and the environment. Environmental & Climatic Settings: Root traces are found in weakly- to well-developed paleosols formed on proximal to distal alluvial and marginal-lacustrine to shallow lacustrine environments. The uppermost part of the rooted horizon represents discontinuity surfaces of variable duration time. The architecture, pattern, and overall depth of roots and rooting structures reflects the depth and fluctuation of soil moisture zones and the water table. In turn, these features are controlled by the local and regional climatic setting. Well-drained soils have deep roots, whereas dry soils have shallow, irregularly dispersed roots. Lateral roots and flank-buttressed trees also associated with wet soil features reflect swampy settings with high water tables. Roots in drier climates are found in clumps and bunches and are associated with carbonate nodules, brecciations, hardpans, and fragipans. fiberous

flank-buttressed 1m

10 cm

rhizome

10 cm

tap roots

1m

108

10 cm

tabular 1m

Cross-section of root patterns

4" diameter core

ROOT TRACES-RHIZOLITHS

B

A 5 cm

5 cm

D

C

26 cm

5 cm

E

F 15 cm 5 cm

Root Traces: A) 3-D view of root casts in Pleistocene coastal dune deposits, San Salvador Island, Bahamas. B) Outcrop cross-section of permineralized roots in pedogenically modified lacustrine carbonate, Oligo-Miocene Ebro Basin, Mequineza, Spain. C) Outcrop cross-section of root traces preserved as reduction/alteration haloes in pedogenically modified alluvial deposits, Eocene Castisant Sandstone, Tremp Basin, Spain. D) Outcrop cross-section of root traces preserved as reduction/alteration haloes in pedogenically modified alluvial deposits, Salt Wash Member, Jurassic Morrison Formation, Utah. E) Outcrop cross-section of downward-branching coalified roots preserved below a coal, Spring Canyon Member, Cretaceous Blackhawk Formation, Helper, Utah. F) Outcrop section of downward-branching roots and roothairs as alteration-reduction haloes in alluvial mature paleosols, red siltstone member, Upper Triassic Chinle Formation, Eagle Basin, Colorado.

109

ROOT TRACES-RHIZOLITHS

A

B mm

C

Roots in Core: A) Cross-section of downward-branching root tubule of carbonate in pedogenically-modified over-bank deposits, Africa. B) Cross-section of multiple-branching root traces preserved clay-filled branching root-hairsin pedogenically modified overbank deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Utah. C) Cross-section of reduction/alteration haloes caused by root traces with carbonate nodules (arrows) in pedogenically modified overbank deposits, Salt Wash Member, Upper Jurassic Morrison Formation, Utah.

110

SNAIL TRACES--SCOLICIA, cf. ISOPODICHNUS Description: Horizontal trails with flattened to slightly raised edges, with or without a sunken floor. Trail diameter from 0.3-2.0+ cm and lengths up to and exceeding 60 cm in outcrop. Trail floor smooth or sometimes with small, slightly impressed furrows. Locomotion trails similar to Scolicia isp., only with transverse sculpture with or without a central furrow /ridge. Also similar to Olivellites isp. Resting traces are walnut- to egg-shaped with either a central, deeper furrow or a series of deeper furrows forming the shape of a walnut. These traces are similar to Isopodichnus or Rusophycus; however, less like the latter because of the lack of distinct transverse ridges and the lack of deep lateral furrows. Interpretation: These traces are the result of snail locomotion (trail) and resting or hiding behavior (walnut-shaped trace). The raised edges are produced by the shell of the snail as it lifts sediment up and over the edges, or sediment is pushed to the sides by the edge of the shell. In some cases, as with marine snails, rasping traces also occur with the trace or are found in place on a trail. The walnut-shapes are produced by the snail pulling itself just below the subsurface. The deeper the animal, the deeper the furrow, but typically only the shell remains above the surface. This may also represent a special feeding behavior. Geologic Range: Devonian to Recent. This represents the age of the oldest probable freshwater snails. Marine snail trails can be as old as the Cambrian (Valentine, 1985). Trophic Classification: The trails represent both locomotion and feeding. As the snail is moving, it is also grazing the surface. Environmental & Climatic Settings: Terrestrial and freshwater snails typically live in alluvial, palustrine, and marginal-lacustrine environments. Terrestrial snails are air-breathers, but aquatic snails obtain their oxygen through gills. The presence of snails in continental environments reflects the presence of ample moisture and water in the system. In some cases, snails are able to aestivate to await the return of waters. These types, however, create rare traces, and they cannot remain in a state of turpor for more than a few years.

raised edge

plan view

raised edge

5 cm

4" diameter core

111

SNAIL TRACES - SCOLICIA, cf. ISOPODICHNUS

A

B

5 cm

D

C

E

5 cm

F

5 cm

Snail Traces-Scolicia, cf. Isopodichnus: A-C) Snail trails assigned to Scolicia isp. in a chute channel sandstone, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. D) A resting or hiding snail trace assigned to cf. Isopoichnus isp. in a chute channel/levee sandstone, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. E) Snail trails of Scolicia isp. crossing oscillation ripples in a chute channel/levee sandstone, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. F) Resting or hiding snail trace assigned to cf. Isopoichnus isp. in the base of a channel sandstone, Brushy Basin Member, Upper Jurassic Morrison Formation, Cleveland-Lloyd Quarry, Utah.

112

SPIDER TRACES Description: Several morphologies of spider traces have been observed. The first type is a vertical burrow composed of a shaft that terminates in a slightly bulbous to spherical chamber. The diameter of the shaft ranges from 0.5-3+ cm and the length varies from 3-30+ cm. The chamber varies in diameter from slightly wider than the diameter of the shaft up to twice the width. The second type of burrow morphology is a horizontal burrow system that is composed one or more interconnected tunnels. The exterior wall is pustulose and reflects the activity of the spider rolling balls of material and for pushing the surface upwards to make the roof of the burrow. Interpretation: These traces are produced by several types of spiders. Wolf spiders commonly produce a vertical burrow with chamber at the terminous. Tarantulas and trap door spiders produce similar burrows, but they are typically at some angle to the surface. Horizontal burrows, including those constructed into the sides of banks, are have been reported less commonly in the literature, but spiders have been observed constructing them (Hasiotis, unpublished data). Geologic Range: Carboniferous? to Recent. Spiders are known from the Siluro-Devonian, but burrows have been interpreted only in Pleistocene eolian sediments (Ahlbrant et al., 1978). Trophic Classification: These traces are used for dwelling, reproduction, and possibly feeding. Environmental & Climatic Settings: These traces are found in marginal-marine and continental environments in subaerial settings that include channel margin, levee, floodplain, dune-dry interdune, and supralittoral lacustrine and marine settings. They are indicators of exposure surfaces that are dry to relatively moist (5-37%). In eolian environments, they tend to be dominant, but their traces have lower preservation potential then in other environments. Climatically, these traces are found in dry, wet-dry, and wet climates. They are rare to absent in areas with very high or standing water tables. ground surface

10 cm

tunnel

chamber

shaft

chamber

tunnel

entrance 4" diameter core

113

SPIDER TRACES

A

B

Spider traces: A) Cross-section of a vertical burrow with a bulbous termination (not visible in photograph), similar in shape to an ice tea spoon in a subaerially exposed sand bar, Platte River, Nebraska. This morphology is assigned to the ichnotaxon Macaonopsis. B) Plan view of horizontal burrow network with a pustulose exterior constructed by a spider (unidentified) along the gently sloping bank of a river, Ischigalasto Basin, Argentina. This burrow morphology is similar to Steinichnus.

114

TERMITE NESTS Description: Mosaic patterns of widely to locally distributed networks of simple and complex galleries (tube length >>> width), small chambers (length = > width = > height), and large chambers (height >>> length >>> width) that form spheres, inclined-ramps, root specific, and root-engulfing shapes. These patterns often build-up, cross-cut, or interpenetrate one another. Chambers range in number from 10 to over 1000, although the number visible in core or outcrop will vary with exposure and ontogenic stage (new vs. old) of the nest. Galleries are connected to chambers and other galleries, 0.3-5.0+ cm in diameter, comprised of single or multiple individual galleries clustered together. The chambers and galleries form a grid-like lattice or an intensely bioturbated sediment fabric in the area surrounding a central cluster of chambers and galleries. This mosaic pattern can range anywhere from < 1m3 to over 1 km3 in volume and depths of 5 to over 30 m. Interpretation: The pattern of chambers and galleries are those most distinctive of nest patterns constructed by extant species of termites (Insecta: Isoptera). Nests are subaerial to subterranean with some portion of the nest above the surface. The nests may engulf dead or living trees and plants. In nests with large portions above the soil surface, the subterranean nest may extend up to 3-4 times the height below ground (= depth). Individual tunnels may extend downward to the water table and extend laterally to locate plant material. Modern and ancient termite nests reflect the social behavior and division of labor among the colony, with workers, soldiers, winged reproductives, and a king and queen. Termites use their nests as storage of plant materials collected from the surface and subsurface, for fungal gardens, for egg rearing, and nurseries, and for the storage of dead termites and wastes. Modern termite nests vary considerably in size from under 1 m3 to over 100-1000+ m2 and 30+ m deep, like those in central Africa. The largest nests are up to 9 m tall and 30 m in diameter at their base; galleries can extent for 10's of meters to the deep African water table, and they can radiate from the nest for 100's of meters (Thorpe, 1949; Behnke, 1977; Hasiotis et al., 1994). Geologic Range: Triassic to Recent (Hasiotis and Dubiel, 1995; Hasiotis and Demko, 1996; Hasiotis, 1997a, in press a, b). Trophic Classification: Termite nests represent multi-use structures that include reproduction, dwelling, gardening, and storage of waste materials and dead nest members. Nests are constructed and engineered; they are excavated and reinforced by using feces or carton. Environmental & Climatic Settings: The architecture of termite nests is incredibly variable; they range from platforms and spheres, to towers and intricately connected tubes or galleries. The presence of termite nests reflect not only the substrate conditions necessary for nest construction, but also the amount of moisture, the availability of plant and animal material (i.e., dung) (Wilson, 1971; Hasiotis and Bown, 1992), and the trophic relationship between termites and their community. Termite nests are typically found in the A and upper B horizons of soils in proximal to distal alluvial and marginal-lacustrine environments. The soil moisture regime represented by nests tend to be upper vadose zone to upper soil water zone (just below surface). Deeper nests reflect lower soil moisture and water table levels, as well as ontogentically older nests. Nests in areas of high water table tend to be very shallow or above ground on trees. Surfaces of long-term exposure may contain multiple generations of crosscutting nests. 115

CROSS-SECTIONS OF TERMITE NESTS

nest center galleries

10 cm

chamber in the form of a ramp

nest

chamber

gallery nest

gallery 4" diameter core

116

4" diameter core

TERMITE NESTS

A

spiral ramp walls

B 5 cm

floors

ramps

rooms

5 cm

D

C

A

galleries

chamber

5 cm chamber

F

5 cm

E

wall with galleries

nest

chambers

5 cm

5 cm

Termite nests: A) Plan view and outcrop cross-section view (B) of termite nests with internal morphology visible, overbank paleosol, Upper Triassic Chinle Formation, Arizona. C) Plan view of termite nest and internal morphology within a complex ground nest, Upper Jurassic Morrison Formation, Utah. D) Plan view of a termite nest in petrified wood, Upper Triassic Chinle Formation, Arizona. E) Plan view section and cross-sectional view (F) of termite nest in outcrop (in dotted line), pedogenically-modified channel-levee complex, Upper Jurassic Morrison Formation, Utah.

117

TERMITE NESTS

A

B

15 cm

200 cm

C

galleries coalesed chambers

D

nest center

5 cm 5 cm

radiating galleries

E

galleries

F

galleries

5 cm

chambers

Termite nests: A) Modern termite (Macrotermes sp.) nest engulfing a dead tree on the Zambezi River floodplain, Zimbabwe, Africa. B) Termite nest constructed on an alluvial plain in buried eolian deposits, eolian facies of the Recapture Member; cross-section of this nest-type in (D), Upper Jurassic Morrison Formation, New Mexico. C) Cross-section of modern termite (Procornitermes sp.) nest showing multi-stacked floors with central spiral ramp in the main pillers; alluvial plain, Argentina. E) Cross-section of subspherical termite nest, Upper Jurassic Morrison Formation, Utah. F) Outcrop plan view of galleries and chambers of a termite nest in a large rhizolith, Upper Jurassic Morrison Formation, Utah.

118

TERMITE NESTS

A

B inner nest

galleries

8 cm

outer nest

outer nest

galleries

nest periphery

nest periphery

galleries

C

D 8 cm

aglomeration of galleries and small chambers

5 cm

E

composite galleries p

m

mm 10-100's of associated galleries

te

si

po

ra

galleries

m co

ps

am er

sit

po

m co

Termite nests in core: A) Cross-section and close-up (B) of a part of a very large spherical termite nest showing the inner and outer nest and nest periphery, Salt Wash Member, Upper Jurassic Morrison Formation, Utah. C) Crosssection showing part of a pillar-type termite nest, Salt Wash Member, Upper Jurassic Morrison Formation, Utah. D) Cross-section showing a composite gallery system associated with a nearby termite nest, Salt Wash Member, Upper Jurassic Morrison Formation, Utah. E) Cross-section showing part of a ramp and gallery system termite nest Salt Wash Member, Upper Jurassic Morrison Formation, Utah.

119

U-SHAPED BURROWS-cf. ARENICOLITES Description: Vertical U-shape tubes 0.2-1.0 cm in diameter that are almost always poorly defined at depth of the U-branches. Only the upper portion of the U-shaped tubes are well defined. Sometimes a reinforced portion of each U-tube above the bedding surface occurs and is from 0.05-0.2 cm in thickness; this thickness is proportionate to the diameter of the tube. Sometimes only a J-shape is present, but it also occurs with the reinforced entrance. Most often, the middle of the U-shape is not preserved, most likely due to collapse after the burrow is abandoned. Similar in appearence to Arenicolites isp., but lacks distinct funnelshapes and raised mounds at the surface and Arenicolites isp. is typically much deeper than the distance between the tubes. Interpretation: These structures are the burrows of insect larvae of the Diptera, particularly the chironamids, and also of mayflies (Insecta: Ephemeroptera). The upper, reinforced tubes are typical of chironamid U-tubes and J-tubes. Some chironamids make a new burrow each day; at night they leave their burrow to feed in the water column and before dawn they return to the bottom to construct another. Mayflies larvae also make these types of burrows and are used for most of the life of the larvae (nymph); mayflies also construct horizontal feeding burrows (Fuersichnus). The larvae leave their burrows to pupate into adults. Geologic Range: Triassic to Recent (e.g., Bown and Kraus, 1983; Hasiotis et al., 1994). Trophic Classification: The burrows most likely represent suspension-feeding, dwelling, and temporary shelter behavior of the chironamids and mayflies. Environmental & Climatic Settings: These insects, and their burrows, are typically found in the freshwater-aquatic settings of alluvial, palustrine, and lacustrine environments. The burrows are typically constructed in low-energy environments in perennial and temporary water bodies of in perennial water settings. In general, these traces are indicators of high moisture and water table levels (typically above ground). Climatically, these organisms occur from the tropics to the cold temperate zones. The highest diversity is in the subtropics and tropics, but great abundances of these organisms can be found in cooler regions. The larvae are released in the early to late spring and typically pupate to adults before the end of summer.

top

ground surface

5 cm

120

4" diameter core

U-SHAPED BURROWS - cf. ARENICOLITES

B

A

15 cm

5 cm

D

C

5 cm

5 cm

U-shaped Burrows--cf. Arenicolites: A) Portions of the tops and bases of U-tubes cut by mudcracks in lacustrine littoral interbedded sandstones and mudstones, Owl Rock Member, Upper Triassic Chinle Formation, Bedrock, Colorado. B) The tops of U-tubes that have poorly defined branches of the U-shape, in a channel/levee interbedded sandstone and mudstone deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. C) The tops of U-tubes that have poorly defined U-branches, in a levee sandstone deposit, Owl Rock Member, Upper Triassic Chinle Formation, Flaming Gorge, Utah. D) Paired openings of U-shaped burrows in littoral lacustrine interbedded sandstone and shale, Tidwell Member, Upper Jurassic Morrison Formation, Blue Mesa, Colorado.

121

VERTEBRATE BURROWS AND NESTS-LARGE AND SMALL Description: Shallow to deep, simple to complex burrows and burrow systems composed of shafts, tunnels, spiral ramps, and chambers. Burrow shapes are subcircular to highly elliptical and diameters range from 2-20+ cm. Overall burrow depths range from 0.1-2+ m. Total burrow lengths range from about 0.5-10+ m in outcrop. Basic burrow shapes include shafts with a bulbous terminous, spiral shafts terminating in tunnels or a chamber, and interconnected tunnels, shafts, spiral shafts, and chambers. The surficial morphology exhibits longitudinal to transverse scratches, bulbous, pustulose, to smooth burrow walls. The simplest structures are hemispherical pits 15-45+ cm in diameter with/without a constricted opening. Interpretation: These burrows and nests were constructed by a host of vertebrates, including mammals, fish, and reptiles (e.g., Voorhies, 1975; Bown and Kraus, 1983; Smith, 1987; Hasiotis and Wellner, 1999). For the most part, the more complex the burrow system, the more complex the behavior (e.g., from solitary, to gregarious, to highly social). See the following sheets for examples of the differnt types. Geologic Range: Devonian to Recent (Voorhies, 1975; Hasiotis and Bown, 1992; Hasiotis et al., 1999; Hasiotis and Wellner, 1999). Trophic Classification: The burrows are used for aestivation (e.g., lungfish), dwelling (e.g., amphibians, birds, mammals, marsupials), reproduction (e.g., reptiles, birds), and feeding (e.g., fish, mammals). The burrow architectures will also vary in complexity based on use and the amount of time the burrows are used. Environmental & Climatic Settings: These burrows and nests are found in proximal to distal alluvial, marginal-eolian and marginal-lacustrine environments. They are indicators of subaerial environments that are rarely to seasonally inundated with water due to flooding or higher water tables. Climatically, some of these structures are used for aestivation due to ephemeral aquatic conditions, hibernation from colder temperatures, or dwelling due to increased temperatures and evaporation. Thus, the structures alone do not provide essential data on climate, but are more useful when combine with data from paleosols, other ichnofossils, and other climatic indicators.

mammal burrow systems 1m

lungfish burrow 50 cm tall

4" diameter core

122

VERTEBRATE BURROWS - LARGE AND SMALL MAMMALS

B

30 cm

A

A

C

T P

C

20 cm

D

5 cm

Vertebrate burrows: A) Excavation of a coyote (C) trying to reach to burrow system of prairie dogs (P), Pleistocene, Sand Hills, NE. B) Excavation of an insectivore (I) that reached a termite nest system (T), Oligocene, Fayum Depression, Egypt. C) Spiral burrow system of a rodent in alluvial overbank deposits, Miocene, Ebro Basin, Spain. D) Several rodent burrow systems in eolain-derived sediment, OligoMiocene, Patagonia, Argentina. Burrow to the left is a spiral entrance shaft, while burrow to the right is composed of multi-level, interconnected tunnels and short spiral shafts.

123

VERTEBRATE BURROWS - LARGE AND SMALL MAMMALS

B

A

8 cm

5 cm

C

5 cm

Vertebrate burrows: A) Ichnogyrus niddens from alluvial overbank deposits, Lower Eocene Willwood Formation, Wyoming. B-C) Mammal burrow systems with variations in architecture due to expansion/ contraction of swelling clays, Salt Wash Member, Upper Jurassic Morrison Formation, Ticaboo, Utah.

124

VERTEBRATE NESTS AND BURROWS - LARGE AND SMALL

A

B

5 cm 5 cm

D

C

3 cm

3 cm

Vertebrate burrows: A-B) Vertebrate hole nests attributed to turtles (small holes) and phytosaurs (large holes) in alluvial proximal overbank deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona. C-D) Lungfish burrows in alluvial proximal overbank sediments with temporary pond deposits, Upper Devonian Catskill Formation, Powys Curve, Pennsylvania.

125

ASSORTED VERTEBRATE TRACKS AND TRACKWAYS Description: Variable digitate tracks (3 to 5 toes/fingers) of manus (front) and pes (rear) of vertebrates. Size of the prints range from 1-70 cm long (heal to tip of longest toe) and up to 60 cm wide (across widest part of track). The tracks occur as isolated impressions to trampled grounds made up of hundreds of superimposed tracks. Preservation of tracks is highly variable, from perfect to barely impressed tracks, to poorly defined impressions. Interpretation: These tracks are formed by several types of vertebrates performing different types of activities. Dinosaurs, pterosaurs, crocodiles, aetosaurs, birds, mammals, and marsupials are just some of the organisms that make tracks. The weight of the organism, firmness of the substrate, and angle of the bedding surface all affect the impression of the tracks. Tracks represent walking, running, sliding, digging, and resting. When a large series of trackways occur together, they have been interpreted as migration trackways of dinosaur or mammal herds (Gillete and Lockley, 1989; Lockley, 1991). Geologic Range: Devonian? to Recent. The range potentially equals the record of amphibious and terrestrial vertebrates (Gillette and Lockley, 1989; Behrensmeyer et al., 1992). Trophic Classification: The tracks and trackways are produced by walking, running, crawling, and sliding of various sized organisms, from several ounces to 100 tons. These behaviors are associated with feeding, mating, evasion, and migration. Environmental & Climatic Settings: The tracks of these organisms are typically found in alluvial, palustrine, dry- to wet-interdune eolian, and marginal-lacustrine environments. The animals and their tracks are in areas associated with vegetation and water. They can live in and traverse areas of marginal sustenance; however, like modern large vertebrates, they cannot exist in these types of environments for long periods. The occurrence of tracks indicate the presence of water or moist substrates. Without such moisture, the tracks themselves can not be preserved. Large vertebrates, like the theropods and sauropods (modern equivalents are the large mammals of the Serengeti), must live in areas where the yearly average of precipitation/evaporation (P/E) approximates 1. They must be able to maintain their body moisture and temperature, as well as maintain their energy levels through nourishment.

Manus (front) and Pes (rear) Pterosaur tracks

Pes (rear)

Dinosaur track

15 cm

40 cm

Manus (front)

Pterosaur track 5 cm Pes (rear)

126

Manus (front) and Pes (rear) Swimming Track (crocodile) 5 cm

4" diameter core

ASSORTED VERTEBRATE TRACKS AND TRACKWAYS

A

B

5 cm

C

5 cm

D

5 cm 5 cm

E

F

30 cm

G

H

5 cm 5 cm

Assorted Vertebrate Tracks: A) Swimming tracks (circles) of a small crocodile, lacustrine littoral sandstone, Tidwell Member, Upper Jurassic Morrison Formation, Blue Mesa, Colorado. (B-D) Pterichnus isp., traces of pterosaur tracks (cirlces) in lacustrine littoral sandstones;,Tidwell Member, Upper Jurassic Morrison Formation, Blue Mesa, Colorado; B and D are equivalent of dinoturbation on a small scale. E) Therapod tracks in reworked eolian coastal plain deposits, Moab Tongue, Middle Jurassic Summerville Formation, Moab, Utah. F-G) Different expressions of phytosaur tracks in alluvial channel-levee deposits, Petrified Forest Member, Upper Triassic Chinle Formation, Petrified Forest National Park, Arizona.

127

WASP NESTS AND COCOONS Description: Associated subvertical shafts and subhorizontal corridors with unlined cells that sometimes contain ovoid to spindle-shaped structures; rarely are the shafts and corridors preserved. Spindled-shaped structures from 0.3-2.0 cm in diameter and 0.6-4.0 cm in length, with width to length ratios of approximately 1:1.75. Some specimens preserve a surficial morphology of subhorizontal ridges less then 0.3 mm in diameter wrapped circumferentially around the shorter diameter of the ovoid. Variations in architecture of associated ovoids include simple, random clusters, large spirally constructed and closed structures, 4 to 15 + cells with shared-wall construction and large multistory rows of cells with enclosures. Interpretation: These structures are the nests and cocoons of solitary to social wasps (Hyemoptera: Sphecidae, Vespidae, Pompilidae). The ovoid, spindled-shaped structures are cocoons that are constructed by the wasp larvae, which hatches from an egg. The female wasp excavates the tube to a flask-shaped, unlined cell that is provisioned with insects killed by the female. In complex social wasp behavior the cells remain open and the larvae are fed by earlier hatched siblings (mostly female). Geologic Range: Triassic to Recent (Hasiotis, 1997a, b, in press a, b). Trophic Classification: nest and cocoons are food-hoarding structures to support a reproductive strategy; nests secondarily serve as a dwelling structure for queen and offspring. Environmental & Climatic Settings: The majority of these insects construct their nests in well-drained immature to mature soils (paleosols) constructed in proximal to distal alluvial and marginal lacustrine environments. They are also found in dune and interdune deposits in semiarid to xeric (wet/dry) settings. Wasps are typically the second group of strictly terrestrial organisms to burrow and nest in newly exposed and deposited substrates once they have reached low soil moisture levels (< 20 %). Nests and cocoons are typically found in the A and upper B horizons of soils. Large cocoon accumulations and crosscutting cocoons and cells represent multiple years (reproductive seasons) of nest site reoccupation.

2 cm

tunnel

cocoons

cells (to become cocoons)

backfilled tunnel

Nest cross-section in soil

128

4" diameter core

WASP NESTS AND COCOONS

B

A

6 cm

4 cm

C

E

D

5 cm

1 cm

F

Wasp trace fossils: A) Cross-section of modern nest with cocoons (arrows), Spain. B) Cross-section of a modern solitary wasp nest, Spain. C) Cross-section of Pleistocene social wasp nest in a coastal eolian dune, San Salvador Island, Bahamas. D) Close-up of cells from nest in (C). E) Miocene solitary wasp nest showing mud pellet construction, Patagonian, Argentina. F) Oligocene social wasp nest showing architecture of combs of cells with central corridor (arrows), Fayum, Egypt.

129

WASP NESTS AND COCOONS

A

3.5 cm

B 5 cm

C mm 5 cm

E

D

5 cm

Wasp trace fossils: A) Paleocene–Eocene cocoons assigned to Eatonichnus isp., southwestern Utah; interpreted here as possible solitary sphecid or presocial vespid wasp cocoons. B) Cross-section Cretaceous paleosol with cocoons (arrows) in the upperpart of the B horizon, Choteau, Montana. C) Core cross-section of a solitary wasp nest cell in a paleosol, Jurassic Morrison Formation, Utah. D) Outcrop plan view of cocoons (arrows) of solitary or gregarious waps, Triassic Chinle Formation, Arizona. E) Collection of cocoons (arrows) weathered out from the outcrop, Triassic Chinle Formation, Arizona.

130

Horizontal surface burrows

Quasi-vertical, U-shaped near-surface burrows Maconopsis

Flying traces

ground surface

10 cm

10 cm

tunnel

chamber

shaft

chamber 4" diameter core

Scolicia

entrance

tunnel

raised edge

4" diameter core

cf. Arenicolites 15 cm

plan view top raised edge

5 cm

4" diameter core

Cochlichnia

ground surface

4" diameter core

5 cm

Dipteran cases

1 cm

2 cm

plan view of trails

1 cm

4" diameter core

5 cm 4" diameter core

Uncrushed and crushed tubes

Tektonargus

Koupichnium 10 cm

saddle case

3.5 cm

Vertebrate footprints

Manus (front) and Pes (rear) Pterosaur tracks 15 cm

40 cm

5 cm

Manus (front)

Manus (front) and Pes (rear)

Pterosaur track

Swimming Track (crocodile) 5 cm

5 cm Pes (rear)

Dinoturbation

4" diameter core

chamber

vadose zone

A A C. symplokonomos Camborygma litomomos

wa

te

shaft

r ta ble

chamber

Cross-section of crayfish burrows phreatic zone through a channel-overbank environment

B

B C. eumekenomos Crayfish burrow in 4" core

Vertebrate burrows

well-formed

toe impression

mammal burrow systems

highly deformed

1m

5 cm

20 cm

Cross-sections of dinosaur tracks

chimney

B

A

kms

paleosurface

deep, well formed

4" diameter core

20 cm

Pes (rear)

Dinosaur track

straight case

Camborygma 1m

Increasing complexity

1 cm

4" diameter core horseshoe crab traces arrows = direction of travel

lungfish burrow 50 cm tall

4" diameter core 4" diameter core

Horizontal near-surface burrows

Multi-oriented subsurface burrows

Steinichnus

Edaphichnium 1 cm

earthworm burrow

burrow wall scratches underside of burrow

5 cm

pellet

4" diameter core

2 cm

Pelecypodichnus

4" diameter core

Adhesive meniscate burrows plan view

paleosurface

2 cm

5 cm

cross-section iew

chambers

meniscae 1 cm

4" diameter core

plan view

Cross-sections of AMB 4" diameter core

2 cm

5 cm

F uers ic hnus

fecal strand

Top view horizontal

1 cm

view into meniscae

Fuersichnus communis

3 cm Side view vertical

F. singularis

4 cm

4" diameter core

meniscae

Scoyenia in 4" core

Scoyenia

131

Multi-component burrows

Root patterns and Burrows in wood fiberous

3 cm

flank-buttressed 1m

10 cm

Monesichnus

rhizome

3 cm

10 cm

Eatonichnus 1 cm

tabular

tap roots shaft

1m

5 cm

3 cm Adhesive meniscate burrows 1m

10 cm

Cross-section of root patterns

4" diameter core

tunnel Dung

cell with dung

1 cm

Scaphichnium

3 cm

Terminal chambers Larval tunnels

shaft

Dung Beetle nest Frass filled gallery provisions

Beetles

Adult tunnel

Beetle nests in wood–Paleoscolytus and Paleobuprestis

dung ball

Coprinisphaera

5 cm 5 cm

Beetle traces in 4" core

Wasp nest

5 cm

2 cm

tunnel cocoons cells (to become cocoons)

Abbreviations of Continental trace fossils

backfilled tunnel Nest cross-section in soil

Bee nest tunnel

Enlargement cap of bee cell

Bee nest with completed cells 5 cm

Cell wall 1 cm

1 cm

cell with closed tunnel newest cell

bee nest with cells in 4" core

Cross-sections of bee cells and nests

Ant nest

5 cm

4 cm chambers

chambers

galleries Cross-sections of ant nests

galleries

4" diameter core

Termite nest

nest center

15 cm

galleries

10 cm

chamber in the form of a ramp

nest

5 cm

chamber gallery nest

gallery 4" diameter core

132

4" diameter core

Increasing complexity

4" diameter core

AMB Ac At Ar Ca Ce Ck Cp Dt Dp Ea Ed Fy Fu Hp H/V Is Km Mn Pb Ps Pe Pl Rh Sm Sl So St Tk Tm Ur Ve Vt Wp

Adhesive meniscate burrows Ancorichnus Ant nest Arenicolites Camborygma Celliforma-bee nest/cells Cochlichnus Coprinisphaera Dinoturbation Dipteran traces Eatonichnus Edaphichnium Flying traces Fuersichnus Haplotichnus horizontal/vertical burrow Isopodichnus Koupichnium Maconopsis Paleobuprestis Paleoscolytus Freshwater clam traces Planolites Rhizoliths Scaphichnium Scolicia Scoyenia Steinichnus Tektonargus Termitichnus Uruguay-bee nest Vertebrate burrow Vertebrate track Wasp nest/cocoon