3.trace Fossil

TRACE FOSSIL

•What is Ichnology?

Ichnology is the study of plant and animal traces. Implicit to this definition is that the traces made by plants and animals reflect some sort of behavior. Ichnology can be divided into two major subdivisions: paleoichnology (the study of ancient traces) and neoichnology (the study of modern traces)

 One

single animal can make thousands and thousands of traces in its lifetime, but it will only leave behind one body when it dies. Because of this, trace fossils are much more common than body fossils

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There are two main types of fossils: body fossils and trace fossils.

Body fossils include any part of the actual animal or plant. Things like bones, teeth, shells, and leaves are considered body fossils (an actual body part of an ancient organism, which includes any casts or molds that were made of the dead body). Trace fossils give us proof of animal life from the past. Trace fossils include things like foot prints, burrows, and fossilized poop. (any indirect evidence of ancient life that reflects some sort of behavior)

Paleontology is the study of ancient life, which means that it can include both the study of trace fossils and body fossils. The study of trace fossils is specifically called paleoichnology.

Among these advantages are: 

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Long Time Ranges - Certain trace fossils, because they were made by similar organisms with similar behavior, have much longer time ranges than most body fossils. Because these trace fossils are useful as environmental indicators for broader periods of time, they are more likely encountered than some body fossils. Abundance - One animal, especially if mobile, can make many traces during its lifetime, whereas it may or may not have its body preserved in the fossil record. Trace fossils made by most organisms should be more abundant than body fossils of the organisms themselves. Common In-situ Occurrence - Unlike body fossils, trace fossils are very rarely transported out of their original substrate. In the majority of cases, trace fossils represent behavior that occurred exactly where you find them.

Preservation Potential - Trace fossils are common in clastic sedimentary rocks that are normally lacking body fossils. This phenomenon is largely a result of poor preservation potential for body fossils in such a medium, whereas trace fossils are preserved or (in some cases) enhanced in these rocks.  Excellent Environmental Indicators - Because behavior is often influenced by environmental factors, trace fossils provide important clues to the original conditions of ancient environments. Environmental factors reflected by trace fossils include salinity, oxygen levels, energy, organismal interactions, and food supplies. 

Disadvantages of trace fossils are relatively fewer than their advantages but mainly center on the fact that one trace maker can make many different traces or many different trace makers can make the same trace. Because of these considerations, most trace fossils have limited value for biostratigraphy.

There are different types of trace fossil: Track: an impression made by a single foot. Trackway: a number of tracks made during a single trip. Trail: an impression made by an animal without legs. Burrows: a hole or holes an animal dug into loose sediment (like mud). Borings: a hole or holes an animal dug into a hard substrate (like wood or rock). Eggs and Nests: shells that at one time would have contained babies and the nests that the babies would have been kept in. Coprolites: poop that has become fossilized (no-longer stinky, but still ickie).

Burrows are excavations made into an unconsolidated substrate.  Tracks are imprints on a sediment surface by an animal with legs.  Trails are imprints on a sediment by a legless animal dragging its body across a surface.  Borings are excavations made into a consolidated substrate, which could include rock or wood. 

Burrows, tracks, and trails are examples of Biogenic sedimentary structures (structures made in an unconsolidated substrate); Borings are examples of bioerosion structures.

 Another

type of trace fossil is biostratification, which can be represented by stromatolites or biogenic graded bedding.  Stratification refers to the layering of sediments, hence biostratification is layering caused by organisms.

 Stromatolites

are biogenic sedimentary structures formed by sediment binding and trapping in cyanobacterial or algal colonies.  Biogenic graded bedding is bedding where organisms mixed the larger particles to the bottom of a sedimentary profile, causing a gradual decrease in particle size upward.

 Fossilized

feces are called coprolites; these are also trace fossils.  Coprolites are valuable clues to the paleodiet of extinct organisms and provide additional information to paleontologists interested in reconstructing ecosystem relationships of fossil plants and animals.

Lastly, eggs and nests are indirect evidence of reproductive behavior and their fossilized equivalents are also considered as trace fossils.  Although some dinosaur eggs have preserved remains of embryos (which are body fossils), the egg itself is a trace fossil.  Nests may or may not include eggs but are structures that were primarily made for facilitating the development of younger animals.  For example, some dinosaur nest sites containing eggs have been discovered, but termite nests without any eggs or body fossils also have been preserved in the fossil record. 

Biogenic Structures  A biogenic structure is a feature caused by an organism while it was still living. This definition effectively separates a biogenic structure from a structure made by the body of a dead organism (such as a drag mark, cast, or mold). The following outline, modified after Frey and Pemberton (1984), provides a breakdown of different categories of biogenic structures and examples of each category: 

Biogenic structures can be classified on the basis of their behavioral association.  These behavioral modes represent basic biological functions that are nearly universal to multicellular organisms, such as feeding, dwelling, and locomotion.  Multiple or overlapping types of behavior can be interpreted from one trace, but the classification is generally applied to the predominant motive of the organism.  For example, a snail might be moving across a surface, hence you would label its behavioral mode as locomotion. However, if the surface has a wonderfully delicious film of organic scum that the snail is consuming as it moves, then the primary purpose for movement was feeding. 

 Different

behavioral modes for biogenic structures were assigned categories by Seilacher (1953).  These categories reflect Latinized names that were meant to standardize the categories; all have the suffix "ichnia" to indicate that they represent traces of the behavior

The diagram shows the interrelationships of the different behavioral modes, their Latinized names, and explanations of each mode. This diagram is modified after Pemberton et al. (1992).

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The types of animal behaviour can be broken up into six broad groups: Dwelling: the animal built the trace and then used it as a home. Resting: the animal simply "took a break". Feeding: the animal made temporary burrows that it stayed in while it was feeding. Farming: the animal made burrow systems that have regular patterns. The animal lived in the burrow permanently and farmed for food.

Locomotion: trackways and trails made by animals "on the move" - traveling from one place to another. Escape: the animal was trying to escape its home and moved up or down in the sediment very quickly.

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Because trace fossils are not actual organisms or parts of organisms, they cannot be given Linnaean names recognized by the ICZN (International Committee on Zoological Nomenclature) as organisms. Nevertheless, morphologically distinctive trace fossils are given genus and species names by ichnologists for the sake of international communication. For example, a simple, unbranched, unlined, horizontal burrow might be given the name Planolites, and varieties of that same basic morphology can be identified as "species" under that same "genus" name (e.g., Planolites montanus). To avoid confusion with binomial nomenclature used in naming body fossils, trace fossils are named as ichnogenera (plural of ichnogenus) and ichnospecies.

the ichnogenus name can not be expected to reflect a specific trace maker.  Consequently, a trilobite trackway may have been made by a species of the trilobite Isotelus, but the trilobite trackway itself might be called Cruziana. When you recall that one of the disadvantages of trace fossils is that the same trace fossil could have been made by many organisms, think of the difficulty of trying to match every Cruziana with each of the hundreds of trilobite genera. Even dinosaur tracks can rarely be matched with a specific dinosaur; most ichnologists are satisfied enough to say that certain trackways were made by sauropods or theropods. 

 ICHNOFACIES

Basic Definition of Ichnofacies 

Assemblages of trace fossils, in association with body fossils and lithologic information, provide excellent clues to parameters of ancient environments. This use of all preserved aspects of an ancient sedimentary deposit for interpreting its original environment of deposition is called facies analysis. If dealing simply with the trace fossils in a sedimentary deposit, you would be interested in describing its environmentally related and contemporaneous trace fossils; in a modern environment, this assemblage is an ichnocoenose. The preserved record of the original ichnocoenose is an ichnofacies

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These ichnofacies, their general environmental association, and representative ichnogenera are (from Pemberton et al., 1992): Trypanites - lithified marine substrates. Entobia Gastrochaenolites Trypanites Teredolites - marine or marginal marine woody substrates. Teredolites Scoyenia - nonmarine substrates. Ancorichnus Cruziana Scoyenia Skolithos Skolithos - high energy, shallow marine substrates. Diplocraterion Monocraterion Ophiomorpha Skolithos

Cruziana - lower energy, circalittoral marine substrates. Arenicolites Aulichnites Cruziana Planolites Teichichnus Thalassinoides Glossifungites - firm (but unlithified) marine substrates. Gastrochaenolites Psilonichnus Rhizocorallium Skolithos Thalassinoides

Psilonichnus - supralittoral, moderate to low energy (beach to backshore). Psilonichnus Macanopsis Zoophycos - circalittoral to bathyal, low energy, marine substrates. Phycosiphon Spirophyton Zoophycos Nereites - bathyal to abyssal, low energy, marine substrates. Cosmoraphe Lorenzinia Nereites Paleodictyon

Applications of Ichnofacies The ichnofacies concept has been applied to petroleum exploration as an aid to interpreting depositional environments.  The interpretation of sedimentary environments helps to assess potential petroleum reservoirs and source rocks on the basis of stratigraphic architecture; laterally adjacent facies succeeding one another vertically (Walther's Law) can be better discerned if the facies are distinctive and identifiable.  Trace fossil assemblages provide an excellent supplementary tool for facies analysis, especially when body fossils are lacking. 

Types of Ichnofacies The trace fossils have remained in appearance rather constant since Cambrian, even if their producers might have been different. The trace fossil assemblages can be divided according the palaeoenvironmental scheme into a number of ichnofacies named after a characteristic trace fossil. The ichnofacies indicate a particular sedimentary facies and can be identified on the basis of its trace fossil assemblage

The typical position of the major ichnofacies in marine and continental environments: Cr - Cruziana; G - Glossifungites; N - Nereites; Tr - Tripanites Ps - Psilonichnus; Sc - Scoyenia; Sk - Skolithos; Z - Zoophycos Te - Teredolites;(after Benton & Harper, 1997)

Wood ground

Rock ground

Firmground Marine

Teredo lites

Trypa nites

Glossi fungites

Fresh water

Loose- and softground Fresh water

Marine

Sedimentology / environment

Energy

Bathymetr y

Grainsiz e

-

Psilonich nus

-

Ruso phycos?

Skoli thos

High

Beach

Sand

Arenico lites?

Arenico lites

Event

Shelf

Sand silt

Lagoon /

Sand, silt

Scoye nia

Fuer sichnus?

Mermia

Backshore

Sand

Cruziana

Med

Nereites

Event

Slope to

Sand, mud

Zoo phycos

Low

abyssal

Mud

shelf

The Skolithos Ichnofacies can be recognized by a low diversity of abundant vertical domichnia burrows (Skolithos, Diplocraterion and Arenicolites), fodinichnia (Ophiomorpha), and fugichnia.

All these traces typically indicate intertidal situations where the organisms have to be able to respond rapidly in stressful conditions. The Skolithos Ichnofacies was at first seen as occurring only in the intertidal zone, but it is also typical of other shifting sand environments, such as the tops of storm sand sheets and the tops of turbidity flows

The Teredolites Ichnofacies is identified by the presence of borings in wood (especially Teredolites), especially those produced by marine bivalves such as the modern ship worm, Teredo.

The Trypanites Ichnofacies is characterized by domichnial borings of worms (Trypanites), bivalves (Gostrochaenolites), barnacles (Rogerella) and sponges (Entobia). These are formed in shoreline rocks or in lithified limestone hard grounds on the seabed. Bioerosion traces made by gastropods and echinoids are rarely preserved in ancient cases

The Zoophycos Ichnofacies is characterized by complex fodinichnia (Zoophycos, and sometimes other deep traces such as Thalassinoides) in tiered arrangements The ichnofacies occurs in a range of water depths between the abyssal zone and the shallow continental shelf, in normal background conditions of sedimentation. The Nereites Ichnofacies may be a matching association found at similar water depths during times of turbidite (event) deposition

The Scoyenia Ichnofacies is characterized by a low diversity trace fossil assemblage, mainly simple horizontal fodinichnia (Scoyenia and Taenidium), with occasional vertical domichnia (Skolithos) and repichnia produced by insects or freshwater shrimps (Cruziana, Isopodichnus). The traces are preserved in fluvial and lacustrine sediments, often in the silts and sands of redbed sequences. Associated subaerial palaeosoils and aeolian sands may contain domichnia and repichnia of insects, and dinosaur and other tetrapod foot-prints.

The Psilonichnus Ichnofacies shows a low diversity assemblage of small vertical burrows with basal living chambers (Macanopsis), narrow sloping T-shaped and Y- shaped burrows (Psilonichnus), root traces, and vertebrate footprints

This ichnofacies is typical of backshore, dune areas, and supratidal flats on the coast

The Nereites Ichnofacies is recognized by the presence of meandering pascichnia (Nereites, Neonereites and Helminthoide), spiral pascichnia (Spirorhaphe), and agrichnia (Paleodictyon and Spirodesmos). Vertical burrows are almost entirely absent

Nereites Ichnofacies viewed in pelagic carbonate ooze

This ichnofacies indicates deep-water environments, including ocean floors and deep marine basins. The trace fossils occur in muds deposited from suspension, and in the mudstones and siltstones of distal turbidites

The Glossifungites Ichnofacies is characterized by domichnia (Glossifungites and Thalassinoides) and sometimes plant root penetration structures. Other behavioural trace fossil types are rare. The traces occur in firm, but not lithified sediments, such as muds and silts in marine intertidal and shallow subtidal zones. The firm grounds may develop in low energy situations such as salt marshes, mud bars, of high intertidal flats, or in shallow marine environments where erosion has stripped off superficial unconsolidated layers of sediment

The Cruziana Ichnofacies shows rich trace fossil diversity, with horizontal repichnia (Cruziana and Aulichnites), cubichnia (Rusophycus, Asteriacites and Lockeia), and vertical burrows This ichnofacies represents mid and distal continental shelf situations, below normal wave base, but may be affected by storm activity

Trace Fossils and Burrows Burrows are a type of trace fossil found commonly in sedimentary rocks. They represent the activity of an organism within the sediment, after the sediment has been deposited. Because of this temporal relationship, burrows normally cross-cut other deposition-related sedimentary structures like bedding and laminations. In some areas, burrowing is so extensive that the sedimentary bedding is pervasively disrupted. The process of disruption of deposition-related sedimentary structures is known as bioturbation.

 Burrow

morphologies are amazingly diverse, and include a variety of wall structures (layered, packed with fecal pellets, lined with mud or sand), sediment infill (sorted or not sorted, similar or different grainsizes), and many geometries (branched tubes, subhorizontal and/or subvertical orientation, curved tubes, U-shaped tubes, mesh geometries, cone-shaped, etc.).  Geometries composed of cylindrical shapes are by far the most common (e.g., a burrow may be branched, but segments will most often be cylindrical).

Thalassinoides sp. burrow. A type of dwelling burrow (domichnia) common in shelf marine environments. This type of burrow is probably produced by a lobster, crayfish, or other type of burrowing crustacean, as indicated by similar modern burrows and occasional preservation of the crustacean within the burrow as a body fossil. This specimen is from the Upper Cretaceous Bad Heart Formation in Alberta. 

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Ophiomorpha sp. burrow. Another type of burrow produced by crustaceans. Note the angular junction between segments of the burrow. From the Upper Cretaeous Semilla Sandstone, New Mexico, U.S.A.

 TRACKS

 A track

is any marking or impression made in a substrate by the foot or hand of an animal. Opinions vary on how many tracks constitute a trackway, but for our purposes  Substrates for track preservation vary considerably but most tracks are formed in unconsolidated sediments and fossil examples show the same preservational bias.  Exceptions include crushing of hard substrates by the feet of heavy animals (i.e., dinosaurs that stepped on bivalve shells or bones) or claw marks left in wood

Tracks made by vertebrates can be classified on the basis of whether they were made by bipedal (twolegged) or quadrupedal (four-legged) animals.  Bipedalism typically involves movement from one opposite foot to another (right to left or left to right), whereas quadrupedalism can use any variation of four limbs (two right and two left) moving in harmony.  The order of foot placement is determined by the behavior of the animal, depending on whether it is walking, trotting, bounding (hopping), or galloping, as well as which direction it is moving. 

TRAILS

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A trail is an impression made on a surface by the body of a limbless animal. Common usage of the term "trail" implies that it is a synonym of "trackway" or that a well-worn path in a terrestrial ecosystem is a trail (as in a "game trail," made by game animals). Although these colloquial meanings are understandable to most people, the distinction between the method of locomotion by a limbed versus a limbless animal is an important one, hence the distinction made here. The surficial aspect of a trail is also distinctive from a burrow, which represents an excavation into a sediment, rather than the displacement or compaction of sedimentary grains on a surface. A trail does not necessarily have to form on an exposed surface; some trails follow horizontal bedding planes within a sedimentary pile, hence these are called intrastratal trails. Trails that formed on an exposed surface are called epistratal trails.

BURROWS

A burrow is any biogenic structure that involves excavation of an unconsolidated (nonindurated) substrate by an organism; the process of forming a burrow by an organisms is burrowing but is also generally called bioturbation (literally "life mixing"). Burrows are primarily associated with excavations in sediment; other types of "burrowing," such as digging into soft tissue (i.e., leaf mines made by insects), are actually more properly termed borings because they permanently erode the structural integrity of a consolidated substrate.  A continuum of biogenic structures in sedimentary rocks can range from softground to firmground to hardground traces; softground and firmground traces are considered as burrows, whereas hardground traces are borings. 

BORINGS

 A boring

is any biogenic structure that involves erosion of an already consolidated substrate by an organism; the process of forming a boring by an organism is bioerosion.  Although most geologists may think of borings as formed exclusively in rocks, other substrates suitable for borings include wood, shells, bones, or eggs. Under the definition given here, toothmarks also could be considered as borings.

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Tracemakers of borings are quite diverse, ranging from algae to tyrannosaurs. A partial listing of bioeroders includes some types of fungi, foraminiferans, poriferans, cnidarians, nematodes, phoronids, bryozoans, brachiopods, sipunculids, polychaetes, bivalves, gastropods, cephalopods, amphineurans, arthropods, echinoids, and fish. Probably the best-known bioeroders are bivalves, of which certain species can bore into rocks and wood. In continental environments, wood has been a preferred substrate for some insect species, such as termites, ants, and bees, as well as woodpeckers. Claw marks left by modern bears on trees are borings, Toothmarks, which I will restrict in usage here to mean marks made by vertebrates with teeth, have been attributed to fossil organisms such as sharks, mosasaurs, or theropods. However, some invertebrates, such as predatory octopi or gastropods, can leave toothlike marks in bivalve shells through their beak and radula, respectively.

A continuum of biogenic structures in sedimentary rocks can range from softground to firmground to hardground traces; this continuum represents a change in relative water content in the original sediment to a state of cementation.  Borings made in marine-related environments often represent a hiatus in deposition that formed a hardground or, in the case of a wood accumulation, a woodground.  Hardgrounds are typically represented by the Trypanites ichnofacies, whereas woodgrounds are represented by the Teredolites ichnofacies.  The Scoyenia ichnofacies includes borings made in continental settings, although subdivision of this ichnofacies would be very helpful for better representation of the diversity of borings reflecting environmentally sensitive factors 

Coprolites Age: ?Jurassic Formation: ?Morrison Location: Utah, USA Collector: Lowentor Museum of Natural History, Stuttgart, Germany Photographer: A. J. Martin Comments: This coprolite has been interpreted as a product of a sauropod because of its large size (about 40 cm diameter from what I recall).

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Age: Formation: Location: Collector: Photographer: A. J. Martin Comments: Although I do not have any further information on this specimen, the presence of some bone material in the coprolite indicates either a carnivore or omnivore, probably mammalian, was the trace maker. I showed this specimen to a tracker who really enjoyed applying his interpretive skills to "scat" that did not have any unpleasant odors associated with it.

 Coprolites

are fossilized feces, which can range from sand-sized pellets made by invertebrates (typically just called pellets by sedimentary petrologists when encountered in thin section) to the large, lump-like masses left by dinosaurs. Coprolites are extremely valuable trace fossils for interpreting paleodiet of organisms.  The study of modern feces is colloquially called "scatology" by trackers and naturalists and is very useful for indirect estimates of animal populations and their ecology in terrestrial environments.

EGGS AND NESTS

An egg is an enclosed, mineralized structure containing an amniote (yolk sac) that helps to nourish the developing embryo.  The structure is a type of protection for the embryo that also keeps all of its nutrients in a restricted space. In contras t, amphibians require a water source for their eggs, hence times of drought (and consequent shrinkage of aquatic habitats) can be detrimental to amphibian reproduction.  Amniotic eggs also have a porous and permeable structure that allows the developing e mbryo to "breathe," thus offering protection but also allowing an exchange with the surrounding environment. 

A nest is a biogenic structure typically containing a clutch and commonly represented by an arrangement of eggs in a semicircular or spiraled pattern. In some instances, a raised area surrounding the eggs will denote the border of the nest, which may be evident as a bowl-like depression.  Nests most likely to have been preserved in the geologic record were on the ground and excavated in soft sediment. Some modern reptiles and a few birds (i.e., penguins) use this strategy and at least some dinosa urs used it, too.  Nests made in trees, like those made by many modern birds, and as vegetative piles on the ground, such as those made by some crocodilians, would have had low preservation potential. 

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Arenicolites isp

Arenicolites is a simple U-shaped burrow oriented perpendicular to bedding. Different types of Arencolites can be interpreted on the basis of the breadth of the U.

Arthophycus isp.

Arthophycus is a horizontal, simple or branched, straight to curved, annulated burrow that shows well-defined and regularly spaced ridges within the burrow fill. Arthrophycus is interpreted as a feeding burrow made by a wormlike animal.

Asteriacites isp.

Asteriacites is a horizontal, fivepointed, star-shaped burrow. Asteriacites is interpreted as a resting trace made by an asterozoan, either a stelleroid or ophiuroid.

Aulichnites isp.

Aulichnites is a horizontally oriented trail having two bilaterally symmetrical convex ridges that are commonly divided by a medial groove. Aulichnites is intepreted as a crawling or grazing trace made by a gastropod.

Barypodus isp.

Barypodus is a track made by a quadrupedal tetrapod vertebrate

Camborygma isp

Camborygma is a large, vertically oriented burrow with some scratchmarks present on burrow exteriors and some specimens show thick mud lining; burrow diameters are 5-10 cm and burrow lengths can be as much as 3-5 meters. Probable tracemaker is a crayfish that burrowed down to the water table in continental environments.

Celliforma isp

Celliforma is a vertically oriented subcylindrical to flask-shaped burrow or boring with a rounded termination; in burrows a remanent of a cap is visible as a ring within the burrow. Probable tracemaker was a bee, which either burrowed into a sandy substrate or bored into wood and used the structure as a brooding chamber.

Chabutolithes isp.

Chabutolithes is a horizontally to obliquely oriented, bilobate burrow showing numerous scratchmarks oblique to perpendicular from the burrow midline (superficially similar to Rusophycus). Probable tracemaker was a burrowing wasp, possibly Pompilidae, that used the structure as a nest.

Cheirotherium isp.

Cheirotherium is a track made by a quadrupedal tetrapod vertebrate

Dactyloidites isp

Dactyloidites is horizontal burrow structure that has a rosetted appearance in plan view; it also can show remanents of a central vertical shaft. Dactyloidites is interpreted as a cumulative deposit-feeding burrow produced by a worm-like animal.

Chondrites isp Chondrites is a branching, vertically to horizontally oriented feeding burrow; the three-dimensional character of Chondrites can be visualized by imagining an upside-down tree, with a main burrow "trunk" connecting to the sediment-water interface and increasingly complex branches downward into the sediment. Chondrites is interpreted as a feeding burrow that is often associated with lowoxygen substrates, although there are exceptions to this generality

Climactichnites isp. Climactichnites is a horizontally oriented trackway characterized by welldefined arched or V-shaped ridges and finer arcuate rill marks. Climactichnites is typically larger (about 15 cm diameter) than most similar trackways, such as Cruziana. Climactichnites has numerous interpretations regarding its tracemaker, including crustaceans, eurypterids, trilobites, and mollusks.

Conichnus isp Conichnus is a vertically oriented burrow with a cone-in-cone structure that tapers in the downward direction. Conichnus differs from Rosellia in that the bottom of the burrow terminates in a point, rather than continuing into a narrower tube. Conichnus is interpreted as a resting trace with evidence of equilibrium as a sessile organism (probably an anemone) moved upward in response to sedimentation

Dimetropus isp.

Dimetropus is a track made by a quadrupedal tetrapod vertebrate and is affiliated with pelycosaurs, such as its supposed tracemaker namesake, Dimetrodon.

Eatonichnus isp.

Eatonichnus is a vertically oriented, annulated, pluglike burrow showing some scratchmarks on the burrow exterior. Probable tracemaker was a burrowing wasp, possibly Sphecidae, that used the burrow as a nest.

Dimorphichnus isp Dimorphichnus is a horizontal trackway with two sets of impressions: thin and long scratch marks that are straight to slightly curved, and short prod marks. Both sets of marks are oblique to the overall direction of movement indicated by the trackway. Dimorphichnus is interpreted as a lateral grazing trace made by a trilobite, where the prod marks are toe impressions and the scratch marks are from raking movement

Diplocraterion isp. Diplocraterion is a U-shaped burrow oriented perpendicular to bedding; spreite are apparent between the limbs of the U. Diplocraterion is interpreted as a dwelling burrow made by an animal that adjusted its burrow either up or down in response to increased sedimentation or erosion, respectively.

Entomichnus isp

Entomichnus is a vertically oriented, spiraled burrow with numerous smaller burrows branching from the main spirals. Probable tracemaker is a termite, specifically a termite nest

Monocraterion isp.

Monocraterion is a simple vertically oriented burrow that shows a funnel-like projection at the top of the burrow; erosion of the burrow top can make this trace fossil indentifiable as Skolithos. Monocraterion is interpreted as a combined dwelling and feeding burrow where the funnel probably served as a trap for prey organisms moving near the burrow opening; the probable tracemaker is a polychaete worm.

Gyrolithes isp

Gyrophyllites isp.

Gyrophyllites is s vertically or obliquely oriented burrow that has a number of leaf-like projections that extend from the central shaft in a helical pattern; Gyrophyllites is interpreted as a feeding burrow made by an animal that made repeated probes into the sediment in a radial pattern. Gyrolithes is a vertically oriented burrow that shows a tightly spiraling form in vertical section; the breadth of the sprial is consistent throughout the length of the burrow. In some instances, Gyrolithes is interpreted as a dwelling structure that may have had some feeding combined; and arthropod tracemaker is probable.

Kouphichnium isp.

Kouphichnium is a horizontally oriented, bilaterally symmetrical trackway that can be quite variable but in best examples shows "birdfoot"-like footprints in association with a medial dragmark. Probable tracemaker was a limulid (horseshoe crab) in either marine or nonmarine environments

Neonereites isp

Neonereites is a meandering, horizontally oriented trail, typically on bedding plane surfaces, filled with single or double pellets. Neonereites is intepreted as a feeding trace from an animal that grazed along a sediment surface, leaving behind regular fecal pellets.

Laoporus isp. Laoporus is a track made by a quadrupedal tetrapod vertebrate and has been attributed to synapsids

Lockeia isp. Lockeia is an ovoid, biconvex, and bilaterally symmetrical trace fossil, typically preserved as a positive relief trace on the bottom of a bed. The overall shape is similar to an almond (and about the same size). Lockeia is interpreted as a bivalve resting trace.

Navahopus isp

Navahopus is a track made by a quadrupedal tetrapod vertebrate. This particular ichnogenus has been attributed to prosauropod tracemakers

Nereites isp. Nereites is a meandering trail with a medial furrow and closely-spaced lobes on either side of the furrow. The meandering can be very tight, causing the trace to occupy a large amount of an affected area. Nereites is interpreted as an feeding trail formed on a sediment surface, perhaps as an intrastratal trace.

Palaeophycus isp.

Palaeophycus is a simple burrow that can (but typically does not) show branching, is oriented horizontal or oblique to bedding, and has a distinctive burrow lining. Palaeophycus is interpreted as a combined feeding and dwelling burrow made by a worm-like animal

Ophiomorpha isp Ophiomorpha is a branching burrow with either horizontal, oblique, or vertical boxlike networks; the burrow exterior is characterized by a knobby texture formed by a pelletal lining, but in some cases only an internal mold of the burrow is evident. Ophiomorpha is interpreted as a combined dwelling and feeding burrow made by a shrimp-like animal; modern callianassid shrimp show the same burrow geometry and pelletal reinforcement of their burrows.

Paleodictyon isp.

Paleodictyon is a polygonal trail oriented parallel to bedding on bedding plane surfaces. The geometry of Paleodictyon is normally a hexagonal network, forming a "honeycomb" pattern. Paleodictyon is interpreted as a "farming" trace, where the tracemaking animal made a systematic mucuous-lined trail that it later grazed after some microbial colonies grew on the organics-rich trail.

Paleohelcura isp

Paleohelcura is a trackway consisting of two parallel rows of tracks; the tracks are typically in groups of three and a medial drag mark is occasionally between the track rows. The probable tracemaker was an arachnid (possibly a scorpion), typically found in rocks formed in continental environments

Paleoscolytus isp. Paleoscolytus is a variously oriented, simple, thin, cylindrical boring found in woody substrates. Probable tracemaker was a wood-boring beetle, such as those of Scolididae.

Phycodes isp.

Phycosiphon isp. Phycosiphon is a horizontally to obliquely oriented burrow having U-shaped loops that make an overall "antler-like" form for the trace. Phycosiphon is interpreted as a feeding burrow made by a worm-like animal

Phycodes is a horizontally to obliquely oriented burrow that shows a "broomlike" branching from a central burrow. Phycodes is interpreted as a feeding burrow made by repeated probes by an animal into the sediment

Psammichnites isp.

Rusophycus isp.

Psammichnites is a horizontally oriented trail with a narrow medial ridge and finer transverse ridges; the overall form is straight to curvaceous, in some cases making loops. Psammichnites is interpreted as a gastropod grazing trace

Rusophycus is a horizontally oriented bilobate, ovoid-shaped burrow that has parallel to subparallel scratch marks laterally extending from a central bisecting plane. . Rusophycus is a resting trace made by a trilobite or a trilobite-like arthropod.

Planolites isp Planolites is a simple meandering burrow oriented horizontal or oblique to bedding; it is typically distinguished from Palaeophycus by its lack of a burrow lining. Planolites is interpreted as a feeding burrow made by a worm-like animal

Psilonichnus isp. Psilonichnus is a vertically oriented burrow that normally shows Ybranching toward the burrow top. Psilonichnus is interpreted as a dwelling burrow for arthropods in dune or marsh environments; the most probable tracemaker was a crab, such as modern Ocypode.

Rhizocorallium isp. Rhizocorallium is a horizontally or obliquely oriented, U-shaped burrow that shows spreite between the limbs of the U. This trace fossil is distinguished from Diplocraterion by its horizontal attitude. Rhizocorallium is interpreted as a feeding burrow where the animal moved horizontally through the sediment in a systematic feeding pattern

Plant Trace Fossils The most common trace fossils left by plant activity are root traces, which show the branching and irregular morphology normally associated with living plant roots.

Rosselia isp. Rosselia is a vertically oriented burrow that shows concentric cone-in-cone structure inside the burrow; the burrow markedly constricts in a downward direction. Rosselia is interpreted as a dwelling burrow where a sessile animal moved its burrow upward as an equilibrium response to sedimentation

Rotodactylus isp

is a track made by a quadrupedal tetrapod vertebrate

Scalarituba isp

Scalarituba is a simple, horizontally or obliquely oriented, meandering burrow that shows a chevron or "scale-like" pattern within the burrow. Scalarituba is interpreted as a feeding burrow where the animal packed its burrow behind it as it moved through the sediment

Schaubcylindrichnus isp.

Schaubcylindrichnus is a vertically to obliquely oriented, well-lined burrow; individual burrows are slightly curved and occur in closely-spaced clusters. Schaubcylindrichnus is interpreted as a dwelling burrow made by a worm-like animal.

Scoyenia isp.

Scoyenia is a horizontal to vertically oriented, simple, straight to slightly curved burrow with a "rope-like" architecture; individual burrows comonly cross one another. Scoyenia is interpreted as a feeding burrow made by an arthropod (possibly a larval beetle) and is typically associated with nonmarine environments, originally formed in moist soils

Spirophycus isp.

Spirophycus is a simple, tightly meandering horizontally oriented trail, parallel to bedding and typically preserved as an impression on a bedding plane surface. Spirophycus is interpreted as a feeding trace left by a worm-like animal as it grazed across a sediment surface or within a bedding interface

Skolithos isp. Skolithos is a simple, tube-like, vertically oriented burrow that typically shows a much greater length versus width. Skolithos is interpreted as a dwelling burrow made by a suspension-feeding animal

Teichichnus isp.

Teichichnus is a simple horizontally or obliquely oriented burrow that shows vertically to obliquely oriented spreite. Teichichnus is interpreted as a feeding burrow, probably made by a deposit-feeding bivalve, that moved its burrow up or down in a vertical plane for systematic feeding

Trichophycus isp.

Trichophycus is a horizontally to obliquely oriented burrow that has a broad "banana-like" U-shape, scratch marks in the burrow wall, and can (but does not necessarily) show some vertically oriented spreite. Trichophycus is interpreted as a combined feeding and dwelling burrow for a large arthropod

Teredolites isp Teredolites is a club-shaped, vertically to obliquely oriented boring that typically shows annulations on the boring wall and is preserved in woodgrounds (coal beds) or as boring casts from woodgrounds. Teredolites is interpreted as a combined feeding and dwelling trace made by wood-boring bivalves in woodgrounds that were submerged under marine water

Thalassinoides isp. Thalassinoides is a branching burrow (Y- or T-shaped branches) with either horizontal, oblique, or vertical box-like networks and enlargements at junctions between some branches. Unlike Ophiomorpha, Thalassinoides has smooth walls. Thalassinoides is interpreted as a combined feeding and dwelling burrow, but has been observed as a boring in some cases. The probable tracemaker was an arthropod

Trypanites isp

Trypanites is a simple, vertically to obliquely oriented boring that can curve slightly and have rounded terminations. Trypanites is interpreted as a dwelling structure where the tracemaker bored into a hard substrate.

Zoophycos isp. Zoophycos is a horizontally to obliquely oriented burrow that shows a helical structure as a result of overlapping U-shaped burrows that have spreite between the U's. (Author's note - this is a difficult burrow for me to describe with words.) Zoophycos is interpreted as a systematic feeding burrow where the animal probed into the sediment in a U-shape swath, then repeated the same type of swath adjacent to the previous swath, moving in a clockwise or counterclockwise direction.

A promising area for future applications of ichnofacies in facies analysis is in hydrogeology and other aspects of environmental geology.  Hydrogeologists often must approximate many of the same parameters (porosity, permeability, facies architecture) sought by petroleum geologists, hence ichnofacies present another important set of data for these geoscientists 