Direct evidence of past life, like footprints preserved in ash, are called ____.

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This article is about a type of fossil. For Dinosaur Footprints park in Massachusetts, see Dinosaur Footprints.

A trace fossil, also known as an ichnofossil (; from Greek: ἴχνος ikhnos "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.

Trace fossils may consist of impressions made on or in the substrate by an organism. For example, burrows, borings (bioerosion), urolites (erosion caused by evacuation of liquid wastes), footprints and feeding marks and root cavities may all be trace fossils.

The term in its broadest sense also includes the remains of other organic material produced by an organism; for example coprolites (fossilized droppings) or chemical markers (sedimentological structures produced by biological means; for example, the formation of stromatolites). However, most sedimentary structures (for example those produced by empty shells rolling along the sea floor) are not produced through the behaviour of an organism and thus are not considered trace fossils.

The study of traces – ichnology .– divides into paleoichnology, or the study of trace fossils, and neoichnology, the study of modern traces. Ichnological science offers many challenges, as most traces reflect the behaviour – not the biological affinity – of their makers. Accordingly, researchers classify trace fossils into form genera, based on their appearance and on the implied behaviour, or ethology, of their makers.

Occurrence[edit]

Traces are better known in their fossilized form than in modern sediments.[1] This makes it difficult to interpret some fossils by comparing them with modern traces, even though they may be extant or even common.[1] The main difficulties in accessing extant burrows stem from finding them in consolidated sediment, and being able to access those formed in deeper water.

This coprolite shows distinct top and bottom jaw bite marks, possibly from a prehistoric gar fish. Discovery location: South Carolina, US; age: Miocene; dimensions: 144.6mm X 63.41mm or 5.7” X 2.5”; weight: 558g (1lbs 4oz)

Trace fossils are best preserved in sandstones;[1] the grain size and depositional facies both contributing to the better preservation. They may also be found in shales and limestones.[1]

Classification[edit]

Trace fossils are generally difficult or impossible to assign to a specific maker. Only in very rare occasions are the makers found in association with their tracks. Further, entirely different organisms may produce identical tracks. Therefore, conventional taxonomy is not applicable, and a comprehensive form of taxonomy has been erected. At the highest level of the classification, five behavioral modes are recognized:[1]

• Domichnia, dwelling structures reflecting the life position of the organism that created it.
• Fodinichnia, three-dimensional structures left by animals which eat their way through sediment, such as deposit feeders;
• Pascichnia, feeding traces left by grazers on the surface of a soft sediment or a mineral substrate;
• Cubichnia, resting traces, in the form of an impression left by an organism on a soft sediment;
• Repichnia, surface traces of creeping and crawling.

Fossils are further classified into form genera, a few of which are even subdivided to a "species" level. Classification is based on shape, form, and implied behavioural mode.

To keep body and trace fossils nomenclatorially separate, ichnospecies are erected for trace fossils. Ichnotaxa are classified somewhat differently in zoological nomenclature than taxa based on body fossils (see trace fossil classification for more information). Examples include:

• Late Cambrian trace fossils from intertidal settings include Protichnites and Climactichnites, amongst others
• Mesozoic dinosaur footprints including ichnogenera such as Grallator, Atreipus and Anomoepus
• Triassic to Recent termite mounds, which can encompass several square kilometers of sediment

Information provided by ichnofossils[edit]

Mesolimulus walchi fossil and track, a rare example of tracks and the creature that made them fossilized together

Trace fossils are important paleoecological and paleoenvironmental indicators, because they are preserved in situ, or in the life position of the organism that made them.[2] Because identical fossils can be created by a range of different organisms, trace fossils can only reliably inform us of two things: the consistency of the sediment at the time of its deposition, and the energy level of the depositional environment.[3] Attempts to deduce such traits as whether a deposit is marine or non-marine have been made, but shown to be unreliable.[3]

Paleoecology[edit]

Trace fossils provide us with indirect evidence of life in the past, such as the footprints, tracks, burrows, borings, and feces left behind by animals, rather than the preserved remains of the body of the actual animal itself. Unlike most other fossils, which are produced only after the death of the organism concerned, trace fossils provide us with a record of the activity of an organism during its lifetime.

Trace fossils are formed by organisms performing the functions of their everyday life, such as walking, crawling, burrowing, boring, or feeding. Tetrapod footprints, worm trails and the burrows made by clams and arthropods are all trace fossils.

Perhaps the most spectacular trace fossils are the huge, three-toed footprints produced by dinosaurs and related archosaurs. These imprints give scientists clues as to how these animals lived. Although the skeletons of dinosaurs can be reconstructed, only their fossilized footprints can determine exactly how they stood and walked. Such tracks can tell much about the gait of the animal which made them, what its stride was, and whether or not the front limbs touched the ground.

However, most trace fossils are rather less conspicuous, such as the trails made by segmented worms or nematodes. Some of these worm castings are the only fossil record we have of these soft-bodied creatures.[citation needed]

Paleoenvironment[edit]

Fossil footprints made by tetrapod vertebrates are difficult to identify to a particular species of animal, but they can provide valuable information such as the speed, weight, and behavior of the organism that made them. Such trace fossils are formed when amphibians, reptiles, mammals or birds walked across soft (probably wet) mud or sand which later hardened sufficiently to retain the impressions before the next layer of sediment was deposited. Some fossils can even provide details of how wet the sand was when they were being produced, and hence allow estimation of paleo-wind directions.[4]

Assemblages of trace fossils occur at certain water depths,[1] and can also reflect the salinity and turbidity of the water column.

Stratigraphic correlation[edit]

Some trace fossils can be used as local index fossils, to date the rocks in which they are found, such as the burrow Arenicolites franconicus which occurs only in a 4 cm (&lt;span class="frac" role="math"&gt;1&lt;span class="sr-only"&gt;+&lt;/span&gt;&lt;span class="num"&gt;1&lt;/span&gt;⁄&lt;span class="den"&gt;2&lt;/span&gt;&lt;/span&gt;&amp;nbsp;in) layer of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Triassic" title="Triassic"&gt;Triassic&lt;/a&gt; &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Muschelkalk" title="Muschelkalk"&gt;Muschelkalk&lt;/a&gt; epoch, throughout wide areas in southern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Germany" title="Germany"&gt;Germany&lt;/a&gt;.&lt;sup id="cite_ref-Schlirf2006_5-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Schlirf2006-5"&gt;[5]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;The base of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; period is defined by the first appearance of the trace fossil &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Treptichnus_pedum" class="mw-redirect" title="Treptichnus pedum"&gt;Treptichnus pedum&lt;/a&gt;&lt;/i&gt;.&lt;sup id="cite_ref-6" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-6"&gt;[6]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;Trace fossils have a further utility as many appear before the organism thought to create them, extending their stratigraphic range.&lt;sup id="cite_ref-Seilacher1994_7-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Seilacher1994-7"&gt;[7]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Ichnofacies"&gt;Ichnofacies&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=7" title="Edit section: Ichnofacies"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;link rel="mw-deduplicated-inline-style"&gt;&lt;div role="note" class="hatnote navigation-not-searchable"&gt;Main article: &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ichnofacies" title="Ichnofacies"&gt;Ichnofacies&lt;/a&gt;&lt;/div&gt; &lt;p&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ichnofacies" title="Ichnofacies"&gt;Ichnofacies&lt;/a&gt; are assemblages of individual trace fossils that occur repeatedly in time and space.&lt;sup id="cite_ref-:0_8-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:0-8"&gt;[8]&lt;/a&gt;&lt;/sup&gt; Palaeontologist &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Adolf_Seilacher" title="Adolf Seilacher"&gt;Adolf Seilacher&lt;/a&gt; pioneered the concept of ichnofacies, whereby geologists infer the state of a sedimentary system at its time of deposition by noting the fossils in association with one another.&lt;sup id="cite_ref-Seilacher1967_1-6" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Seilacher1967-1"&gt;[1]&lt;/a&gt;&lt;/sup&gt; The principal ichnofacies recognized in the literature are &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Skolithos" title="Skolithos"&gt;Skolithos&lt;/a&gt;&lt;/i&gt;, &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cruziana" title="Cruziana"&gt;Cruziana&lt;/a&gt;&lt;/i&gt;, &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Zoophycos" title="Zoophycos"&gt;Zoophycos&lt;/a&gt;&lt;/i&gt;, &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Nereites" title="Nereites"&gt;Nereites&lt;/a&gt;, Glossifungites, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Scoyenia" title="Scoyenia"&gt;Scoyenia&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trypanites" title="Trypanites"&gt;Trypanites&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Teredolites" title="Teredolites"&gt;Teredolites&lt;/a&gt;,&lt;/i&gt; and &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Psilonichnus" class="mw-redirect" title="Psilonichnus"&gt;Psilonichus&lt;/a&gt;&lt;/i&gt;.&lt;sup id="cite_ref-:0_8-1" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:0-8"&gt;[8]&lt;/a&gt;&lt;/sup&gt;&lt;sup id="cite_ref-:1_9-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:1-9"&gt;[9]&lt;/a&gt;&lt;/sup&gt; These assemblages are not random. In fact, the assortment of fossils preserved are primarily constrained by the environmental conditions in which the trace-making organisms dwelt.&lt;sup id="cite_ref-:1_9-1" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:1-9"&gt;[9]&lt;/a&gt;&lt;/sup&gt; Water depth, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Salinity" title="Salinity"&gt;salinity&lt;/a&gt;, hardness of the substrate, dissolved oxygen, and many other environmental conditions control which organisms can inhabit particular areas.&lt;sup id="cite_ref-:0_8-2" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:0-8"&gt;[8]&lt;/a&gt;&lt;/sup&gt; Therefore, by documenting and researching changes in ichnofacies, scientists can interpret changes in environment.&lt;sup id="cite_ref-:1_9-2" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-:1-9"&gt;[9]&lt;/a&gt;&lt;/sup&gt; For example, ichnological studies have been utilized across mass extinction boundaries, such as the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event" title="Cretaceous–Paleogene extinction event"&gt;Cretaceous-Paleogene mass extinction&lt;/a&gt;, to aid in understanding environmental factors involved in mass extinction events.&lt;sup id="cite_ref-10" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-10"&gt;[10]&lt;/a&gt;&lt;/sup&gt;&lt;sup id="cite_ref-11" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-11"&gt;[11]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Inherent_bias"&gt;Inherent bias&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=8" title="Edit section: Inherent bias"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:312px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Hadrosaur_tracks.png" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Hadrosaur_tracks.png/310px-Hadrosaur_tracks.png" decoding="async" width="310" height="206" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Hadrosaur_tracks.png/465px-Hadrosaur_tracks.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Hadrosaur_tracks.png/620px-Hadrosaur_tracks.png 2x" data-file-width="1810" data-file-height="1201"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Hadrosaur_tracks.png" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;Diagram showing how dinosaur footprints are preserved in different deposits&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;p&gt;Most trace fossils are known from marine deposits.&lt;sup id="cite_ref-12" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-12"&gt;[12]&lt;/a&gt;&lt;/sup&gt; Essentially, there are two types of traces, either exogenic ones, which are made on the surface of the sediment (such as tracks) or endogenic ones, which are made within the layers of sediment (such as burrows). &lt;/p&gt;&lt;p&gt;Surface trails on sediment in shallow marine environments stand less chance of fossilization because they are subjected to wave and current action. Conditions in quiet, deep-water environments tend to be more favorable for preserving fine trace structures. &lt;/p&gt;&lt;p&gt;Most trace fossils are usually readily identified by reference to similar phenomena in modern environments. However, the structures made by organisms in recent sediment have only been studied in a limited range of environments, mostly in coastal areas, including &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tidal_flat" class="mw-redirect" title="Tidal flat"&gt;tidal flats&lt;/a&gt;.&lt;sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap"&gt;[&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"&gt;&lt;span title="This claim needs references to reliable sources. (January 2008)"&gt;citation needed&lt;/span&gt;&lt;/a&gt;&lt;/i&gt;]&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Evolution"&gt;Evolution&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=9" title="Edit section: Evolution"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Climactichnites_-_Todd_Gass.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/6/61/Climactichnites_-_Todd_Gass.jpg/220px-Climactichnites_-_Todd_Gass.jpg" decoding="async" width="220" height="165" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/61/Climactichnites_-_Todd_Gass.jpg/330px-Climactichnites_-_Todd_Gass.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/61/Climactichnites_-_Todd_Gass.jpg/440px-Climactichnites_-_Todd_Gass.jpg 2x" data-file-width="2048" data-file-height="1536"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Climactichnites_-_Todd_Gass.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Climactichnites" title="Climactichnites"&gt;Climactichnites&lt;/a&gt; wilsoni&lt;/i&gt;, probably trails from a slug-like animal, from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Blackberry_Hill" title="Blackberry Hill"&gt;Blackberry Hill&lt;/a&gt;, central &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Wisconsin" title="Wisconsin"&gt;Wisconsin&lt;/a&gt;. &lt;i&gt;The ruler in the background is 45&amp;nbsp;cm (18&amp;nbsp;in) long.&lt;/i&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;p&gt;The earliest complex trace fossils, not including microbial traces such as &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Stromatolites" class="mw-redirect" title="Stromatolites"&gt;stromatolites&lt;/a&gt;, date to &lt;span class="nourlexpansion plainlinks" style="white-space:nowrap"&gt;&lt;a target="_blank" rel="nofollow" class="external text" href="https://geoltime.github.io/?Ma=2000%E2%80%931800"&gt;2,000&amp;nbsp;to&amp;nbsp;1,800&lt;/a&gt; million years ago&lt;/span&gt;. This is far too early for them to have an animal origin, and they are thought to have been formed by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Amoeba" title="Amoeba"&gt;amoebae&lt;/a&gt;.&lt;sup id="cite_ref-Bengtson2009_13-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Bengtson2009-13"&gt;[13]&lt;/a&gt;&lt;/sup&gt; Putative "burrows" dating as far back as &lt;span class="nourlexpansion plainlinks" style="white-space:nowrap"&gt;&lt;a target="_blank" rel="nofollow" class="external text" href="https://geoltime.github.io/?Ma=1,100"&gt;1,100&lt;/a&gt; million years&lt;/span&gt; may have been made by animals which fed on the undersides of microbial mats, which would have shielded them from a chemically unpleasant ocean;&lt;sup id="cite_ref-Seilacher1998_14-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Seilacher1998-14"&gt;[14]&lt;/a&gt;&lt;/sup&gt; however their uneven width and tapering ends make a biological origin so difficult to defend&lt;sup id="cite_ref-Budd2000_15-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Budd2000-15"&gt;[15]&lt;/a&gt;&lt;/sup&gt; that even the original author no longer believes they are authentic.&lt;sup id="cite_ref-16" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-16"&gt;[16]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;The first evidence of burrowing which is widely accepted dates to the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ediacaran" title="Ediacaran"&gt;Ediacaran&lt;/a&gt; (Vendian) period, around &lt;span class="nourlexpansion plainlinks" style="white-space:nowrap"&gt;&lt;a target="_blank" rel="nofollow" class="external text" href="https://geoltime.github.io/?Ma=560"&gt;560&lt;/a&gt;&amp;nbsp;million years ago&lt;/span&gt;.&lt;sup id="cite_ref-17" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-17"&gt;[17]&lt;/a&gt;&lt;/sup&gt; During this period the traces and burrows basically are horizontal on or just below the seafloor surface. Such traces must have been made by motile organisms with heads, which would probably have been &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bilateria" title="Bilateria"&gt;bilateran&lt;/a&gt; &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Animal" title="Animal"&gt;animals&lt;/a&gt;.&lt;sup id="cite_ref-18" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-18"&gt;[18]&lt;/a&gt;&lt;/sup&gt; The traces observed imply simple behaviour, and point to organisms feeding above the surface and burrowing for protection from predators.&lt;sup id="cite_ref-Dzik2007_19-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Dzik2007-19"&gt;[19]&lt;/a&gt;&lt;/sup&gt; Contrary to widely circulated opinion that Ediacaran burrows are only horizontal the vertical burrows &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Skolithos" title="Skolithos"&gt;Skolithos&lt;/a&gt;&lt;/i&gt; are also known.&lt;sup id="cite_ref-Fedonkin_1985_20-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Fedonkin_1985-20"&gt;[20]&lt;/a&gt;&lt;/sup&gt; The producers of burrows &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Skolithos" title="Skolithos"&gt;Skolithos&lt;/a&gt; declinatus&lt;/i&gt; from the Vendian (&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ediacaran" title="Ediacaran"&gt;Ediacaran&lt;/a&gt;) beds in &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Russia" title="Russia"&gt;Russia&lt;/a&gt; with date &lt;span class="nourlexpansion plainlinks" style="white-space:nowrap"&gt;&lt;a target="_blank" rel="nofollow" class="external text" href="https://geoltime.github.io/?Ma=555.3"&gt;555.3&lt;/a&gt;&amp;nbsp;million years ago&lt;/span&gt; have not been identified; they might have been filter feeders subsisting on the nutrients from the suspension. The density of these burrows is up to 245 burrows/dm&lt;sup&gt;2&lt;/sup&gt;.&lt;sup id="cite_ref-21" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-21"&gt;[21]&lt;/a&gt;&lt;/sup&gt; Some Ediacaran trace fossils have been found directly associated with body fossils. &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Yorgia" title="Yorgia"&gt;Yorgia&lt;/a&gt;&lt;/i&gt; and &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Dickinsonia" title="Dickinsonia"&gt;Dickinsonia&lt;/a&gt;&lt;/i&gt; are often found at the end of long pathways of trace fossils matching their shape.&lt;sup id="cite_ref-Ivantsov2002_22-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Ivantsov2002-22"&gt;[22]&lt;/a&gt;&lt;/sup&gt; The feeding was performed in a mechanical way, supposedly the ventral side of body these organisms was covered with &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cilia" class="mw-redirect" title="Cilia"&gt;cilia&lt;/a&gt;.&lt;sup id="cite_ref-Oslo_2008_23-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Oslo_2008-23"&gt;[23]&lt;/a&gt;&lt;/sup&gt; The potential &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Mollusc" class="mw-redirect" title="Mollusc"&gt;mollusc&lt;/a&gt; related &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Kimberella" title="Kimberella"&gt;Kimberella&lt;/a&gt;&lt;/i&gt; is associated with scratch marks, perhaps formed by a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Radula" title="Radula"&gt;radula&lt;/a&gt;,&lt;sup id="cite_ref-Fedonkin2007_24-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Fedonkin2007-24"&gt;[24]&lt;/a&gt;&lt;/sup&gt; further traces from &lt;span class="nourlexpansion plainlinks" style="white-space:nowrap"&gt;&lt;a target="_blank" rel="nofollow" class="external text" href="https://geoltime.github.io/?Ma=555"&gt;555&lt;/a&gt;&amp;nbsp;million years ago&lt;/span&gt; appear to imply active crawling or burrowing activity.&lt;sup id="cite_ref-Martin2000_25-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Martin2000-25"&gt;[25]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;As the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; got underway, new forms of trace fossil appeared, including vertical burrows (e.g. &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Diplocraterion" title="Diplocraterion"&gt;Diplocraterion&lt;/a&gt;&lt;/i&gt;) and traces normally attributed to &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Arthropod" title="Arthropod"&gt;arthropods&lt;/a&gt;.&lt;sup id="cite_ref-26" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-26"&gt;[26]&lt;/a&gt;&lt;/sup&gt; These represent a “widening of the behavioural repertoire”,&lt;sup id="cite_ref-ConwayMorris1989_27-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-ConwayMorris1989-27"&gt;[27]&lt;/a&gt;&lt;/sup&gt; both in terms of abundance and complexity.&lt;sup id="cite_ref-28" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-28"&gt;[28]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;Trace fossils are a particularly significant source of data from this period because they represent a data source that is not directly connected to the presence of easily fossilized hard parts, which are rare during the Cambrian. Whilst exact assignment of trace fossils to their makers is difficult, the trace fossil record seems to indicate that at the very least, large, bottom-dwelling, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Symmetry_(biology)#Bilateral_symmetry" class="mw-redirect" title="Symmetry (biology)"&gt;bilaterally symmetrical&lt;/a&gt; organisms were rapidly diversifying during the early &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt;.&lt;sup id="cite_ref-29" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-29"&gt;[29]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;Further, less rapid&lt;sup class="noprint Inline-Template" style="white-space:nowrap"&gt;[&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability"&gt;&lt;span title="The material near this tag needs to be fact-checked with the cited source(s). (April 2008)"&gt;verification needed&lt;/span&gt;&lt;/a&gt;&lt;/i&gt;]&lt;/sup&gt; diversification occurred since,&lt;sup class="noprint Inline-Template" style="white-space:nowrap"&gt;[&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability"&gt;&lt;span title="The material near this tag needs to be fact-checked with the cited source(s). (April 2008)"&gt;verification needed&lt;/span&gt;&lt;/a&gt;&lt;/i&gt;]&lt;/sup&gt; and many traces have been converged upon independently by unrelated groups of organisms.&lt;sup id="cite_ref-Seilacher1967_1-7" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Seilacher1967-1"&gt;[1]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;Trace fossils also provide our earliest evidence of animal life on land.&lt;sup id="cite_ref-30" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-30"&gt;[30]&lt;/a&gt;&lt;/sup&gt; Evidence of the first animals that appear to have been fully terrestrial dates to the Cambro-Ordovician and is in the form of trackways.&lt;sup id="cite_ref-MacNaughton2002_31-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-MacNaughton2002-31"&gt;[31]&lt;/a&gt;&lt;/sup&gt; Trackways from the Ordovician &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tumblagooda_sandstone" class="mw-redirect" title="Tumblagooda sandstone"&gt;Tumblagooda sandstone&lt;/a&gt; allow the behaviour of other terrestrial organisms to be determined.&lt;sup id="cite_ref-Trewin1995_4-1" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Trewin1995-4"&gt;[4]&lt;/a&gt;&lt;/sup&gt; The trackway &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Protichnites" title="Protichnites"&gt;Protichnites&lt;/a&gt;&lt;/i&gt; represents traces from an amphibious or terrestrial arthropod going back to the Cambrian.&lt;sup id="cite_ref-ColletteEtAl2012_32-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-ColletteEtAl2012-32"&gt;[32]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Common_ichnogenera"&gt;Common ichnogenera&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=10" title="Edit section: Common ichnogenera"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Petroxestes_pera_Ordovician_Ohio.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Petroxestes_pera_Ordovician_Ohio.jpg/220px-Petroxestes_pera_Ordovician_Ohio.jpg" decoding="async" width="220" height="130" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Petroxestes_pera_Ordovician_Ohio.jpg/330px-Petroxestes_pera_Ordovician_Ohio.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Petroxestes_pera_Ordovician_Ohio.jpg/440px-Petroxestes_pera_Ordovician_Ohio.jpg 2x" data-file-width="3480" data-file-height="2052"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Petroxestes_pera_Ordovician_Ohio.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Petroxestes" title="Petroxestes"&gt;Petroxestes&lt;/a&gt;&lt;/i&gt; borings in a hardground from the Upper &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ordovician" title="Ordovician"&gt;Ordovician&lt;/a&gt; of southern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ohio" title="Ohio"&gt;Ohio&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:RusophycusOrdovician.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d8/RusophycusOrdovician.jpg/220px-RusophycusOrdovician.jpg" decoding="async" width="220" height="130" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/RusophycusOrdovician.jpg/330px-RusophycusOrdovician.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d8/RusophycusOrdovician.jpg/440px-RusophycusOrdovician.jpg 2x" data-file-width="1889" data-file-height="1118"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:RusophycusOrdovician.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Rusophycus" title="Rusophycus"&gt;Rusophycus&lt;/a&gt;&lt;/i&gt; trace fossil from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ordovician" title="Ordovician"&gt;Ordovician&lt;/a&gt; of southern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ohio" title="Ohio"&gt;Ohio&lt;/a&gt;. Scale bar is 10 mm.&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Skolithos.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Skolithos.jpg/220px-Skolithos.jpg" decoding="async" width="220" height="162" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Skolithos.jpg/330px-Skolithos.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Skolithos.jpg/440px-Skolithos.jpg 2x" data-file-width="2000" data-file-height="1472"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Skolithos.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Skolithos" title="Skolithos"&gt;Skolithos&lt;/a&gt;&lt;/i&gt; trace fossil. Scale bar is 10 mm.&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:ThalassinoidesIsrael.JPG" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/8/83/ThalassinoidesIsrael.JPG/220px-ThalassinoidesIsrael.JPG" decoding="async" width="220" height="165" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/83/ThalassinoidesIsrael.JPG/330px-ThalassinoidesIsrael.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/83/ThalassinoidesIsrael.JPG/440px-ThalassinoidesIsrael.JPG 2x" data-file-width="1000" data-file-height="750"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:ThalassinoidesIsrael.JPG" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Thalassinoides" title="Thalassinoides"&gt;Thalassinoides&lt;/a&gt;&lt;/i&gt;, burrows produced by crustaceans, from the Middle &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Jurassic" title="Jurassic"&gt;Jurassic&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Makhtesh" title="Makhtesh"&gt;Makhtesh&lt;/a&gt; Qatan, southern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Israel" title="Israel"&gt;Israel&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Trypanites01.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/8/84/Trypanites01.jpg/220px-Trypanites01.jpg" decoding="async" width="220" height="147" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/84/Trypanites01.jpg/330px-Trypanites01.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/84/Trypanites01.jpg/440px-Trypanites01.jpg 2x" data-file-width="3731" data-file-height="2490"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Trypanites01.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trypanites" title="Trypanites"&gt;Trypanites&lt;/a&gt;&lt;/i&gt; borings in an Upper &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ordovician" title="Ordovician"&gt;Ordovician&lt;/a&gt; &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Hardground" class="mw-redirect" title="Hardground"&gt;hardground&lt;/a&gt; from northern Kentucky. The borings are filled with diagenetic &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Dolomite_(mineral)" title="Dolomite (mineral)"&gt;dolomite&lt;/a&gt; (yellowish). Note that the boring on the far right cuts through a shell in the matrix.&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Trace_fossils_in_Uruguay.JPG" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Trace_fossils_in_Uruguay.JPG/220px-Trace_fossils_in_Uruguay.JPG" decoding="async" width="220" height="165" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Trace_fossils_in_Uruguay.JPG/330px-Trace_fossils_in_Uruguay.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Trace_fossils_in_Uruguay.JPG/440px-Trace_fossils_in_Uruguay.JPG 2x" data-file-width="2576" data-file-height="1932"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Trace_fossils_in_Uruguay.JPG" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;Ophiomorpha&lt;/i&gt; and &lt;i&gt;Thalassinoides&lt;/i&gt; trace fossils produced by crustaceans found at Camacho formation from the Late &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Miocene" title="Miocene"&gt;Miocene&lt;/a&gt; in &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Colonia_Department" title="Colonia Department"&gt;Colonia Department&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Uruguay" title="Uruguay"&gt;Uruguay&lt;/a&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;ul&gt;&lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Anoigmaichnus" title="Anoigmaichnus"&gt;Anoigmaichnus&lt;/a&gt;&lt;/i&gt; is a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bioclaustration" title="Bioclaustration"&gt;bioclaustration&lt;/a&gt;. It occurs in the Ordovician bryozoans. Apertures of &lt;i&gt;Anoigmaichnus&lt;/i&gt; are elevated above their hosts' growth surfaces, forming short chimney-like structures.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Arachnostega&amp;action=edit&amp;redlink=1" class="new" title="Arachnostega (page does not exist)"&gt;Arachnostega&lt;/a&gt;&lt;/i&gt; is the name given to the irregular, branching burrows in the sediment fill of shells. They are visible on the surface of steinkerns. Their traces are known from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; period onwards.&lt;sup id="cite_ref-VinnWilsonZatonToom2014_33-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-VinnWilsonZatonToom2014-33"&gt;[33]&lt;/a&gt;&lt;/sup&gt;&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Asteriacites" title="Asteriacites"&gt;Asteriacites&lt;/a&gt;&lt;/i&gt; is the name given to the five-rayed fossils found in rocks and they record the resting place of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Starfish" title="Starfish"&gt;starfish&lt;/a&gt; on the sea floor. &lt;i&gt;Asteriacites&lt;/i&gt; are found in European and American rocks, from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ordovician" title="Ordovician"&gt;Ordovician&lt;/a&gt; period onwards, and are numerous in rocks from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Jurassic" title="Jurassic"&gt;Jurassic&lt;/a&gt; period of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Germany" title="Germany"&gt;Germany&lt;/a&gt;.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Burrinjuckia" title="Burrinjuckia"&gt;Burrinjuckia&lt;/a&gt;&lt;/i&gt; is a bioclaustration. &lt;i&gt;Burrinjuckia &lt;/i&gt; includes outgrowths of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Brachiopod" title="Brachiopod"&gt;brachiopod&lt;/a&gt;'s secondary shell with a hollow interior in the mantle cavity of a brachiopod.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Chondrites_(genus)" title="Chondrites (genus)"&gt;Chondrites&lt;/a&gt;&lt;/i&gt; (not to be confused with stony meteorites of the same name) are small branching burrows of the same diameter, which superficially resemble the roots of a plant. The most likely candidate for having constructed these burrows is a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Nematode" title="Nematode"&gt;nematode&lt;/a&gt; (roundworm). &lt;i&gt;Chondrites&lt;/i&gt; are found in marine sediments from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; period of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Paleozoic" title="Paleozoic"&gt;Paleozoic&lt;/a&gt; onwards. They are especially common in sediments which were deposited in reduced-oxygen environments.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Climactichnites" title="Climactichnites"&gt;Climactichnites&lt;/a&gt;&lt;/i&gt; is the name given to surface trails and burrows that consist of a series of chevron-shaped raised cross bars that are usually flanked on either side by a parallel ridge. They somewhat resemble tire tracks, and are larger (typically about 10&amp;nbsp;cm or 4&amp;nbsp;in wide) than most of the other trace fossils made by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Invertebrates" class="mw-redirect" title="Invertebrates"&gt;invertebrates&lt;/a&gt;. The trails were produced on sandy tidal flats during &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; time. While the identity of the animal is still conjectural, it may have been a large &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Slug" title="Slug"&gt;slug&lt;/a&gt;-like animal – its trails produced as it crawled over and processed the wet sand to obtain food.&lt;sup id="cite_ref-34" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-34"&gt;[34]&lt;/a&gt;&lt;/sup&gt;&lt;sup id="cite_ref-35" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-35"&gt;[35]&lt;/a&gt;&lt;/sup&gt;&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cruziana" title="Cruziana"&gt;Cruziana&lt;/a&gt;&lt;/i&gt; are excavation trace marks made on the sea floor which have a two-lobed structure with a central groove. The lobes are covered with scratch marks made by the legs of the excavating organism, usually a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trilobite" title="Trilobite"&gt;trilobite&lt;/a&gt; or allied arthropod. &lt;i&gt;Cruziana&lt;/i&gt; are most common in marine sediments formed during the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Paleozoic" title="Paleozoic"&gt;Paleozoic&lt;/a&gt; era, particularly in rocks from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; and &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ordovician" title="Ordovician"&gt;Ordovician&lt;/a&gt; periods. Over 30 ichnospecies of &lt;i&gt;Cruziana&lt;/i&gt; have been identified. See also &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Isopodichnus" title="Isopodichnus"&gt;Isopodichnus&lt;/a&gt;.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Entobia" title="Entobia"&gt;Entobia&lt;/a&gt;&lt;/i&gt; is a boring produced by endolithic clionaid &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sponges" class="mw-redirect" title="Sponges"&gt;sponges&lt;/a&gt; consisting of galleries excavated in a carbonate substrate; often has swollen chambers with connecting canals.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Gastrochaenolites" title="Gastrochaenolites"&gt;Gastrochaenolites&lt;/a&gt;&lt;/i&gt; are clavate (club-shaped) borings also produced in calcareous hard substrates, usually by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bivalve" class="mw-redirect" title="Bivalve"&gt;bivalves&lt;/a&gt;.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Oikobesalon" title="Oikobesalon"&gt;Oikobesalon&lt;/a&gt;&lt;/i&gt; is an unbranched, elongate burrow with single-entrance and circular cross-section produced by terebellid polychaetes. They are covered with thin lining which has a transverse ornamentation in the form of fusiform annulation.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Petroxestes" title="Petroxestes"&gt;Petroxestes&lt;/a&gt;&lt;/i&gt; is a shallow groove boring produced by mytilacean bivalves in carbonate hard substrates.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Protichnites" title="Protichnites"&gt;Protichnites&lt;/a&gt;&lt;/i&gt; consists of two rows of tracks and a linear depression between the two rows. The tracks are believed to have been made by the walking appendages of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Arthropod" title="Arthropod"&gt;arthropods&lt;/a&gt;. The linear depression is thought to be the result of a dragging tail. The structures bearing this name were typically made on the tidal flats of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Paleozoic" title="Paleozoic"&gt;Paleozoic&lt;/a&gt; seas, but similar ones extend into the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cenozoic" title="Cenozoic"&gt;Cenozoic&lt;/a&gt;.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Rhizocorallium" title="Rhizocorallium"&gt;Rhizocorallium&lt;/a&gt;&lt;/i&gt; is a type of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Burrow" title="Burrow"&gt;burrow&lt;/a&gt;, the inclination of which is typically within 10° of the bedding planes of the sediment. These burrows can be very large, over a meter long in sediments that show good preservation, e.g. &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Jurassic" title="Jurassic"&gt;Jurassic&lt;/a&gt; rocks of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Yorkshire" title="Yorkshire"&gt;Yorkshire&lt;/a&gt; Coast (eastern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/United_Kingdom" title="United Kingdom"&gt;United Kingdom&lt;/a&gt;), but the width is usually only up to &lt;link rel="mw-deduplicated-inline-style"&gt;2 centimetres (&lt;span class="frac" role="math"&gt;&lt;span class="num"&gt;3&lt;/span&gt;⁄&lt;span class="den"&gt;4&lt;/span&gt;&lt;/span&gt;&amp;nbsp;in), restricted by the size of the organisms producing it. It is thought that they represent fodinichnia as the animal (probably a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Nematode" title="Nematode"&gt;nematode&lt;/a&gt;) scoured the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sediment" title="Sediment"&gt;sediment&lt;/a&gt; for food.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Rogerella" title="Rogerella"&gt;Rogerella&lt;/a&gt;&lt;/i&gt; is a small pouch-shaped boring with a slit-like aperture currently produced by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Acrothoracica" title="Acrothoracica"&gt;acrothoracican&lt;/a&gt; &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Barnacles" class="mw-redirect" title="Barnacles"&gt;barnacles&lt;/a&gt;.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Rusophycus" title="Rusophycus"&gt;Rusophycus&lt;/a&gt;&lt;/i&gt; are bilobed "resting traces" associated with trilobites and other arthropods such as horseshoe crabs.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Skolithos" title="Skolithos"&gt;Skolithos&lt;/a&gt;&lt;/i&gt;: One well-known occurrence of Cambrian trace fossils from this period is the famous '&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Pipe_Rock" class="mw-redirect" title="Pipe Rock"&gt;Pipe Rock&lt;/a&gt;' of northwest &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Scotland" title="Scotland"&gt;Scotland&lt;/a&gt;. The 'pipes' that give the rock its name are closely packed straight tubes- which were presumably made by some kind of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Worm" title="Worm"&gt;worm&lt;/a&gt;-like organism. The name given to this type of tube or burrow is &lt;i&gt;Skolithos&lt;/i&gt;, which may be 30&amp;nbsp;cm (12&amp;nbsp;in) in length and between &lt;link rel="mw-deduplicated-inline-style"&gt;2 and 4&amp;nbsp;cm (&lt;span class="frac" role="math"&gt;&lt;span class="num"&gt;3&lt;/span&gt;⁄&lt;span class="den"&gt;4&lt;/span&gt;&lt;/span&gt; and &lt;span class="frac" role="math"&gt;1&lt;span class="sr-only"&gt;+&lt;/span&gt;&lt;span class="num"&gt;1&lt;/span&gt;⁄&lt;span class="den"&gt;2&lt;/span&gt;&lt;/span&gt;&amp;nbsp;in) in diameter. Such traces are known worldwide from sands and &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sandstone" title="Sandstone"&gt;sandstones&lt;/a&gt; deposited in shallow water environments, from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cambrian" title="Cambrian"&gt;Cambrian&lt;/a&gt; period (542–488 &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Annum" class="mw-redirect" title="Annum"&gt;Ma&lt;/a&gt;) onwards.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Thalassinoides" title="Thalassinoides"&gt;Thalassinoides&lt;/a&gt;&lt;/i&gt; are burrows which occur parallel to the bedding plane of the rock and are extremely abundant in rocks, worldwide, from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Jurassic" title="Jurassic"&gt;Jurassic&lt;/a&gt; period onwards. They are repeatedly branched, with a slight swelling present at the junctions of the tubes. The burrows are cylindrical and vary from &lt;link rel="mw-deduplicated-inline-style"&gt;2 to 5&amp;nbsp;cm (&lt;span class="frac" role="math"&gt;&lt;span class="num"&gt;3&lt;/span&gt;⁄&lt;span class="den"&gt;4&lt;/span&gt;&lt;/span&gt; to 2&amp;nbsp;in) in diameter. &lt;i&gt;Thalassinoides&lt;/i&gt; sometimes contain scratch marks, droppings or the bodily remains of the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Crustacean" title="Crustacean"&gt;crustaceans&lt;/a&gt; which made them.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Teichichnus" title="Teichichnus"&gt;Teichichnus&lt;/a&gt;&lt;/i&gt; has a distinctive form produced by the stacking of thin 'tongues' of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sediment" title="Sediment"&gt;sediment&lt;/a&gt;, atop one another. They are again believed to be fodinichnia, with the organism adopting the habit of retracing the same route through varying heights of the sediment, which would allow it to avoid going over the same area. These 'tongues' are often quite sinuous, reflecting perhaps a more nutrient-poor environment in which the feeding animals had to cover a greater area of sediment, in order to acquire sufficient nourishment.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tremichnus" title="Tremichnus"&gt;Tremichnus&lt;/a&gt;&lt;/i&gt; is an embedment structure (i.e. &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bioclaustration" title="Bioclaustration"&gt;bioclaustration&lt;/a&gt;) formed by an organism that inhibited growth of the crinoid host stereom.&lt;/li&gt; &lt;li&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trypanites" title="Trypanites"&gt;Trypanites&lt;/a&gt;&lt;/i&gt; are elongated cylindrical &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bioerosion" title="Bioerosion"&gt;borings&lt;/a&gt; in calcareous substrates such as shells, carbonate &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Hardground" class="mw-redirect" title="Hardground"&gt;hardgrounds&lt;/a&gt; and &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Limestones" class="mw-redirect" title="Limestones"&gt;limestones&lt;/a&gt;. Usually produced by worms of various types and &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sipunculids" class="mw-redirect" title="Sipunculids"&gt;sipunculids&lt;/a&gt;.&lt;/li&gt;&lt;/ul&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Other_notable_trace_fossils"&gt;Other notable trace fossils&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=11" title="Edit section: Other notable trace fossils"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;p&gt;Less ambiguous than the above ichnogenera, are the traces left behind by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Invertebrate" title="Invertebrate"&gt;invertebrates&lt;/a&gt; such as &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Hibbertopterus" title="Hibbertopterus"&gt;Hibbertopterus&lt;/a&gt;&lt;/i&gt;, a giant "sea scorpion" or &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Eurypterid" title="Eurypterid"&gt;eurypterid&lt;/a&gt; of the early &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Paleozoic" title="Paleozoic"&gt;Paleozoic&lt;/a&gt; era. This marine &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Arthropod" title="Arthropod"&gt;arthropod&lt;/a&gt; produced a spectacular track preserved in Scotland.&lt;sup id="cite_ref-36" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-36"&gt;[36]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bioerosion" title="Bioerosion"&gt;Bioerosion&lt;/a&gt; through time has produced a magnificent record of borings, gnawings, scratchings and scrapings on hard substrates. These trace fossils are usually divided into macroborings&lt;sup id="cite_ref-37" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-37"&gt;[37]&lt;/a&gt;&lt;/sup&gt; and microborings.&lt;sup id="cite_ref-38" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-38"&gt;[38]&lt;/a&gt;&lt;/sup&gt;&lt;sup id="cite_ref-39" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-39"&gt;[39]&lt;/a&gt;&lt;/sup&gt; Bioerosion intensity and diversity is punctuated by two events. One is called the Ordovician Bioerosion Revolution (see Wilson &amp;amp; Palmer, 2006) and the other was in the Jurassic.&lt;sup id="cite_ref-40" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-40"&gt;[40]&lt;/a&gt;&lt;/sup&gt; For a comprehensive bibliography of the bioerosion literature, please see the External links below. &lt;/p&gt;&lt;p&gt;The oldest types of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tetrapod" title="Tetrapod"&gt;tetrapod&lt;/a&gt; tail-and-footprints date back to the latter &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Devonian" title="Devonian"&gt;Devonian&lt;/a&gt; period. These &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Vertebrate" title="Vertebrate"&gt;vertebrate&lt;/a&gt; impressions have been found in &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ireland" title="Ireland"&gt;Ireland&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Scotland" title="Scotland"&gt;Scotland&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Pennsylvania" title="Pennsylvania"&gt;Pennsylvania&lt;/a&gt;, and &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Australia" title="Australia"&gt;Australia&lt;/a&gt;. A sandstone slab containing the track of tetrapod, dated to 400 million years, is amongst the oldest evidence of a vertebrate walking on land.&lt;sup id="cite_ref-Vickers-Rich2993_41-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Vickers-Rich2993-41"&gt;[41]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt;&lt;p&gt;Important &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Human_evolution" title="Human evolution"&gt;human&lt;/a&gt; trace fossils are the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Laetoli" title="Laetoli"&gt;Laetoli&lt;/a&gt; (&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tanzania" title="Tanzania"&gt;Tanzania&lt;/a&gt;) footprints, imprinted in volcanic ash 3.7 &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Annum" class="mw-redirect" title="Annum"&gt;Ma&lt;/a&gt; (million years ago) – probably by an early &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Australopithecus" title="Australopithecus"&gt;Australopithecus&lt;/a&gt;.&lt;sup id="cite_ref-RaichlenEtal1010_42-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-RaichlenEtal1010-42"&gt;[42]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Confusion_with_other_types_of_fossils"&gt;Confusion with other types of fossils&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=12" title="Edit section: Confusion with other types of fossils"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;div class="thumb tright"&gt;&lt;div class="thumbinner" style="width:222px"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:AsteriacitesDevonianOhio.jpg" class="image"&gt;&lt;img alt="" src="https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/AsteriacitesDevonianOhio.jpg/220px-AsteriacitesDevonianOhio.jpg" decoding="async" width="220" height="166" class="thumbimage" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e0/AsteriacitesDevonianOhio.jpg/330px-AsteriacitesDevonianOhio.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e0/AsteriacitesDevonianOhio.jpg/440px-AsteriacitesDevonianOhio.jpg 2x" data-file-width="3378" data-file-height="2556"&gt;&lt;/a&gt; &lt;div class="thumbcaption"&gt;&lt;div class="magnify"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:AsteriacitesDevonianOhio.jpg" class="internal" title="Enlarge"&gt;&lt;/a&gt;&lt;/div&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Asteriacites" title="Asteriacites"&gt;Asteriacites&lt;/a&gt;&lt;/i&gt; (sea star trace fossil) from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Devonian" title="Devonian"&gt;Devonian&lt;/a&gt; of northeastern Ohio. It appears at first to be an external mold of the body, but the sediment piled between the rays shows that it is a burrow.&lt;/div&gt;&lt;/div&gt;&lt;/div&gt; &lt;p&gt;Trace fossils are not body casts. The &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ediacara_biota" class="mw-redirect" title="Ediacara biota"&gt;Ediacara biota&lt;/a&gt;, for instance, primarily comprises the casts of organisms in sediment. Similarly, a footprint is not a simple replica of the sole of the foot, and the resting trace of a seastar has different details than an impression of a seastar. &lt;/p&gt;&lt;p&gt;Early paleobotanists misidentified a wide variety of structures they found on the bedding planes of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Sedimentary_rocks" class="mw-redirect" title="Sedimentary rocks"&gt;sedimentary rocks&lt;/a&gt; as fucoids (&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Fucales" title="Fucales"&gt;Fucales&lt;/a&gt;, a kind of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Brown_algae" title="Brown algae"&gt;brown algae&lt;/a&gt; or &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Seaweed" title="Seaweed"&gt;seaweed&lt;/a&gt;). However, even during the earliest decades of the study of ichnology, some fossils were recognized as animal footprints and burrows. Studies in the 1880s by &lt;a target="_blank" href="https://en.wikipedia.org/wiki/A._G._Nathorst" class="mw-redirect" title="A. G. Nathorst"&gt;A. G. Nathorst&lt;/a&gt; and &lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Joseph_F._James&amp;action=edit&amp;redlink=1" class="new" title="Joseph F. James (page does not exist)"&gt;Joseph F. James&lt;/a&gt; comparing 'fucoids' to modern traces made it increasingly clear that most of the specimens identified as fossil fucoids were animal trails and burrows. True fossil fucoids are quite rare. &lt;/p&gt;&lt;p&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Pseudofossil" title="Pseudofossil"&gt;Pseudofossils&lt;/a&gt;, which are &lt;i&gt;not&lt;/i&gt; true fossils, should also not be confused with ichnofossils, which are true indications of prehistoric life. &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="Gallery_of_trace_fossils"&gt;Gallery of trace fossils&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=13" title="Edit section: Gallery of trace fossils"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;ul class="gallery mw-gallery-traditional"&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:35.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:FaringdonCobble.JPG" class="image" title="Numerous borings in a Cretaceous cobble, Faringdon, England; see Wilson (1986)"&gt;&lt;img alt="Numerous borings in a Cretaceous cobble, Faringdon, England; see Wilson (1986)" src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/FaringdonCobble.JPG/180px-FaringdonCobble.JPG" decoding="async" width="180" height="139" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/FaringdonCobble.JPG/270px-FaringdonCobble.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7f/FaringdonCobble.JPG/360px-FaringdonCobble.JPG 2x" data-file-width="2830" data-file-height="2184"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Numerous borings in a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cretaceous" title="Cretaceous"&gt;Cretaceous&lt;/a&gt; cobble, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Faringdon" title="Faringdon"&gt;Faringdon&lt;/a&gt;, &lt;a target="_blank" href="https://en.wikipedia.org/wiki/England" title="England"&gt;England&lt;/a&gt;; see Wilson (1986) &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:37.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:BoredEncrustedShell.JPG" class="image" title="Sponge borings (Entobia) and encrusters on a modern bivalve shell, North Carolina"&gt;&lt;img alt="Sponge borings (Entobia) and encrusters on a modern bivalve shell, North Carolina" src="https://upload.wikimedia.org/wikipedia/commons/thumb/1/10/BoredEncrustedShell.JPG/180px-BoredEncrustedShell.JPG" decoding="async" width="180" height="135" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/10/BoredEncrustedShell.JPG/270px-BoredEncrustedShell.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/10/BoredEncrustedShell.JPG/360px-BoredEncrustedShell.JPG 2x" data-file-width="700" data-file-height="525"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Sponge borings (&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Entobia" title="Entobia"&gt;Entobia&lt;/a&gt;&lt;/i&gt;) and encrusters on a modern bivalve shell, North Carolina &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:39.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG" class="image" title="Entobia from the Prairie Bluff Chalk Formation (Upper Cretaceous). Preserved as a cast of the excavations."&gt;&lt;img alt="Entobia from the Prairie Bluff Chalk Formation (Upper Cretaceous). Preserved as a cast of the excavations." src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG/180px-Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG" decoding="async" width="180" height="131" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/76/Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG/270px-Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/76/Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG/360px-Entobia_Prairie_Bluff_Chalk_Formation_Cretaceous.JPG 2x" data-file-width="3010" data-file-height="2193"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;Entobia&lt;/i&gt; from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Prairie_Bluff_Chalk_Formation" class="mw-redirect" title="Prairie Bluff Chalk Formation"&gt;Prairie Bluff Chalk Formation&lt;/a&gt; (Upper &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cretaceous" title="Cretaceous"&gt;Cretaceous&lt;/a&gt;). Preserved as a cast of the excavations. &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:56px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Gyrochorte_convex_epirelief.jpg" class="image" title="Trace fossil Gyrochorte from the Carmel Formation (Middle Jurassic) of SW Utah."&gt;&lt;img alt="Trace fossil Gyrochorte from the Carmel Formation (Middle Jurassic) of SW Utah." src="https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/Gyrochorte_convex_epirelief.jpg/180px-Gyrochorte_convex_epirelief.jpg" decoding="async" width="180" height="98" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/be/Gyrochorte_convex_epirelief.jpg/270px-Gyrochorte_convex_epirelief.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/be/Gyrochorte_convex_epirelief.jpg/360px-Gyrochorte_convex_epirelief.jpg 2x" data-file-width="6000" data-file-height="3280"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Trace fossil &lt;i&gt;Gyrochorte&lt;/i&gt; from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Carmel_Formation" title="Carmel Formation"&gt;Carmel Formation&lt;/a&gt; (Middle Jurassic) of SW Utah. &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:37.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Helminthopsis01.JPG" class="image" title="Helminthopsis ichnosp., a trace fossil from the Logan Formation (Lower Carboniferous) of Wooster, Ohio"&gt;&lt;img alt="Helminthopsis ichnosp., a trace fossil from the Logan Formation (Lower Carboniferous) of Wooster, Ohio" src="https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Helminthopsis01.JPG/180px-Helminthopsis01.JPG" decoding="async" width="180" height="135" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Helminthopsis01.JPG/270px-Helminthopsis01.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Helminthopsis01.JPG/360px-Helminthopsis01.JPG 2x" data-file-width="2272" data-file-height="1704"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;Helminthopsis&lt;/i&gt; ichnosp., a trace fossil from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Logan_Formation" title="Logan Formation"&gt;Logan Formation&lt;/a&gt; (Lower &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Carboniferous" title="Carboniferous"&gt;Carboniferous&lt;/a&gt;) of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Wooster,_Ohio" title="Wooster, Ohio"&gt;Wooster, Ohio&lt;/a&gt; &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:36px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Gigandipus.JPG" class="image" title="Gigandipus, a dinosaur footprint in the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern Utah"&gt;&lt;img alt="Gigandipus, a dinosaur footprint in the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern Utah" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Gigandipus.JPG/180px-Gigandipus.JPG" decoding="async" width="180" height="138" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Gigandipus.JPG/270px-Gigandipus.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Gigandipus.JPG/360px-Gigandipus.JPG 2x" data-file-width="1500" data-file-height="1152"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;Gigandipus&lt;/i&gt;, a &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Dinosaur" title="Dinosaur"&gt;dinosaur&lt;/a&gt; footprint in the Lower &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Jurassic" title="Jurassic"&gt;Jurassic&lt;/a&gt; Moenave Formation at the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/St._George_Dinosaur_Discovery_Site" title="St. George Dinosaur Discovery Site"&gt;St. George Dinosaur Discovery Site&lt;/a&gt; at Johnson Farm, southwestern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Utah" title="Utah"&gt;Utah&lt;/a&gt; &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:37.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:CretaceousLockeia121911.jpg" class="image" title="Lockeia from the Dakota Formation (Upper Cretaceous)"&gt;&lt;img alt="Lockeia from the Dakota Formation (Upper Cretaceous)" src="https://upload.wikimedia.org/wikipedia/commons/thumb/1/14/CretaceousLockeia121911.jpg/180px-CretaceousLockeia121911.jpg" decoding="async" width="180" height="135" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/14/CretaceousLockeia121911.jpg/270px-CretaceousLockeia121911.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/14/CretaceousLockeia121911.jpg/360px-CretaceousLockeia121911.jpg 2x" data-file-width="2000" data-file-height="1500"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;Lockeia&lt;/i&gt; from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Dakota_Formation" title="Dakota Formation"&gt;Dakota Formation&lt;/a&gt; (Upper Cretaceous) &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:45.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:DevonianLockeia121911.jpg" class="image" title="Lockeia from the Chagrin Shale (Upper Devonian) of northeastern Ohio. This is an example of the trace fossil ethological group Fugichnia."&gt;&lt;img alt="Lockeia from the Chagrin Shale (Upper Devonian) of northeastern Ohio. This is an example of the trace fossil ethological group Fugichnia." src="https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/DevonianLockeia121911.jpg/180px-DevonianLockeia121911.jpg" decoding="async" width="180" height="119" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/01/DevonianLockeia121911.jpg/270px-DevonianLockeia121911.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/01/DevonianLockeia121911.jpg/360px-DevonianLockeia121911.jpg 2x" data-file-width="3000" data-file-height="1975"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;Lockeia&lt;/i&gt; from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Chagrin_Shale" title="Chagrin Shale"&gt;Chagrin Shale&lt;/a&gt; (Upper Devonian) of northeastern &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ohio" title="Ohio"&gt;Ohio&lt;/a&gt;. This is an example of the trace fossil ethological group &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Fugichnia" title="Fugichnia"&gt;Fugichnia&lt;/a&gt;. &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:58.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Gnathichnus_Cenomanian_020413.JPG" class="image" title="Gnathichnus pentax echinoid trace fossil on an oyster from the Cenomanian of Hamakhtesh Hagadol, southern Israel"&gt;&lt;img alt="Gnathichnus pentax echinoid trace fossil on an oyster from the Cenomanian of Hamakhtesh Hagadol, southern Israel" src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Gnathichnus_Cenomanian_020413.JPG/180px-Gnathichnus_Cenomanian_020413.JPG" decoding="async" width="180" height="93" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/Gnathichnus_Cenomanian_020413.JPG/270px-Gnathichnus_Cenomanian_020413.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/db/Gnathichnus_Cenomanian_020413.JPG/360px-Gnathichnus_Cenomanian_020413.JPG 2x" data-file-width="1560" data-file-height="808"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;&lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Gnathichnus" title="Gnathichnus"&gt;Gnathichnus pentax&lt;/a&gt;&lt;/i&gt; echinoid trace fossil on an oyster from the &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Cenomanian" title="Cenomanian"&gt;Cenomanian&lt;/a&gt; of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Hamakhtesh_Hagadol" class="mw-redirect" title="Hamakhtesh Hagadol"&gt;Hamakhtesh Hagadol&lt;/a&gt;, southern Israel &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:30.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Naticid_borehole_Calvert.jpg" class="image" title="Naticid boring in Stewartia from the Calvert Formation, Zone 10, Calvert County, Maryland (Miocene)"&gt;&lt;img alt="Naticid boring in Stewartia from the Calvert Formation, Zone 10, Calvert County, Maryland (Miocene)" src="https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Naticid_borehole_Calvert.jpg/180px-Naticid_borehole_Calvert.jpg" decoding="async" width="180" height="149" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Naticid_borehole_Calvert.jpg/270px-Naticid_borehole_Calvert.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Naticid_borehole_Calvert.jpg/360px-Naticid_borehole_Calvert.jpg 2x" data-file-width="2340" data-file-height="1932"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Naticid boring in &lt;i&gt;Stewartia&lt;/i&gt; from the Calvert Formation, Zone 10, Calvert County, Maryland (Miocene) &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:38.5px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Trace_fossils_Bull_Fork_Ordovician_OH.JPG" class="image" title="Trace fossils as convex hyporeliefs on bottom of bed; Bull Fork Formation (Upper Ordovician); Caesar Creek, Ohio"&gt;&lt;img alt="Trace fossils as convex hyporeliefs on bottom of bed; Bull Fork Formation (Upper Ordovician); Caesar Creek, Ohio" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/Trace_fossils_Bull_Fork_Ordovician_OH.JPG/180px-Trace_fossils_Bull_Fork_Ordovician_OH.JPG" decoding="async" width="180" height="133" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Trace_fossils_Bull_Fork_Ordovician_OH.JPG/270px-Trace_fossils_Bull_Fork_Ordovician_OH.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/43/Trace_fossils_Bull_Fork_Ordovician_OH.JPG/360px-Trace_fossils_Bull_Fork_Ordovician_OH.JPG 2x" data-file-width="3120" data-file-height="2312"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Trace fossils as convex hyporeliefs on bottom of bed; Bull Fork Formation (Upper Ordovician); Caesar Creek, Ohio &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;li class="gallerybox" style="width:215px"&gt;&lt;div style="width:215px"&gt; &lt;div class="thumb" style="width:210px"&gt;&lt;div style="margin:15px auto"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/File:Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG" class="image" title="Inverted trace fossil of an unidentified tridactyl ornithopod"&gt;&lt;img alt="Inverted trace fossil of an unidentified tridactyl ornithopod" src="https://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG/155px-Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG" decoding="async" width="155" height="180" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG/232px-Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG/310px-Tridactyl_ornithopod_dinosaur_track_YORYM-1998.335.JPG 2x" data-file-width="1764" data-file-height="2049"&gt;&lt;/a&gt;&lt;/div&gt;&lt;/div&gt; &lt;div class="gallerytext"&gt; &lt;p&gt;Inverted trace fossil of an unidentified &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Tridactyl" class="mw-redirect" title="Tridactyl"&gt;tridactyl&lt;/a&gt; &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Ornithopod" class="mw-redirect" title="Ornithopod"&gt;ornithopod&lt;/a&gt; &lt;/p&gt; &lt;/div&gt; &lt;/div&gt;&lt;/li&gt; &lt;/ul&gt; &lt;h2&gt;&lt;span class="mw-headline" id="History"&gt;History&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=14" title="Edit section: History"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;p&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Charles_Darwin" title="Charles Darwin"&gt;Charles Darwin&lt;/a&gt;'s &lt;i&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/The_Formation_of_Vegetable_Mould_through_the_Action_of_Worms" class="mw-redirect" title="The Formation of Vegetable Mould through the Action of Worms"&gt;The Formation of Vegetable Mould through the Action of Worms&lt;/a&gt;&lt;/i&gt;&lt;sup id="cite_ref-43" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-43"&gt;[a]&lt;/a&gt;&lt;/sup&gt; is an example of a very early work on ichnology, describing &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Bioturbation" title="Bioturbation"&gt;bioturbation&lt;/a&gt; and, in particular, the burrowing of &lt;a target="_blank" href="https://en.wikipedia.org/wiki/Earthworms" class="mw-redirect" title="Earthworms"&gt;earthworms&lt;/a&gt;.&lt;sup id="cite_ref-Donovan_44-0" class="reference"&gt;&lt;a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil#cite_note-Donovan-44"&gt;[43]&lt;/a&gt;&lt;/sup&gt; &lt;/p&gt; &lt;h2&gt;&lt;span class="mw-headline" id="See_also"&gt;See also&lt;/span&gt;&lt;span class="mw-editsection"&gt;&lt;span class="mw-editsection-bracket"&gt;[&lt;/span&gt;&lt;a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&amp;action=edit&amp;section=15" title="Edit section: See also"&gt;edit&lt;/a&gt;&lt;span class="mw-editsection-bracket"&gt;]&lt;/span&gt;&lt;/span&gt;&lt;/h2&gt; &lt;style data-mw-deduplicate="TemplateStyles:r998391716"&gt;.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</p><div class="div-col div-col-small"> <ul><li><a target="_blank" href="https://en.wikipedia.org/wiki/20th_century_in_ichnology" title="20th century in ichnology">20th century in ichnology</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Bioerosion" title="Bioerosion">Bioerosion</a>&nbsp;– Erosion of hard substrates by living organisms</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Brutalichnus" title="Brutalichnus">Brutalichnus</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Bird_ichnology" title="Bird ichnology">Bird ichnology</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Egg_fossil" title="Egg fossil">Egg fossil</a>&nbsp;– Fossilized remains of eggs laid by ancient animals</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Ichnite" class="mw-redirect" title="Ichnite">Ichnite</a> - fossilized footprints</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Ichnofacies" title="Ichnofacies">Ichnofacies</a>&nbsp;– Trace fossil</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/List_of_index_fossils" title="List of index fossils">Index fossil</a>&nbsp;– Fossils used to define and identity geologic periods</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/List_of_non-Dinosauria_fossil_trackway_articles" title="List of non-Dinosauria fossil trackway articles">List of non-Dinosauria fossil trackway articles</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Neoichnology" title="Neoichnology">Neoichnology</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Nereites" title="Nereites"><i>Nereites irregularis</i></a>&nbsp;– Trace fossil</li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Spoor_(animal)" title="Spoor (animal)">Spoor (animal)</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Trace_fossil_classification" title="Trace fossil classification">Trace fossil classification</a></li> <li><a target="_blank" href="https://en.wikipedia.org/wiki/Way_up_structure" title="Way up structure">Way up structure</a></li></ul> </div> <h2><span class="mw-headline" id="References">References</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a target="_blank" href="https://en.wikipedia.org/w/index.php?title=Trace_fossil&action=edit&section=16" title="Edit section: References">edit</a><span class="mw-editsection-bracket">]</span></span></h2> <style data-mw-deduplicate="TemplateStyles:r1011085734">.mw-parser-output .reflist{font-size:90%;margin-bottom:0.5em;list-style-type:decimal}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

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Further reading[edit]

1. ^ Darwin, C. R. (1881), The formation of vegetable mould, through the action of worms, with observations on their habits, London: John Murray, retrieved 26 September 2014

• Bromley, R.G., 1970. "Borings as trace fossils and Entobia cretacea Portlock as an example", pp. 49–90. In: Crimes, T.P. and Harper, J.C. (eds.), Trace Fossils. Geological Journal Special Issue 3.
• Bromley, R.G., 2004. "A stratigraphy of marine bioerosion". In: The application of ichnology to palaeoenvironmental and stratigraphic analysis. (Ed. D. McIlroy), Geological Society of London, Special Publications 228:455–481.
• Palmer, T.J., 1982. "Cambrian to Cretaceous changes in hardground communities". Lethaia 15:309–323.
• Seilacher, Adolf (2007). Trace Fossil Analysis. Springer-Verlag. 226 p. ISBN 9783540472254.
• Vinn, O. & Wilson, M.A. (2010). "Occurrence of giant borings of Osprioneides kampto in the lower Silurian (Sheinwoodian) stromatoporoids of Saaremaa, Estonia". Ichnos. 17 (3): 166–171. doi:10.1080/10420940.2010.502478. S2CID 128990588. Retrieved 2014-01-10.
• Wilson, M.A., 1986. "Coelobites and spatial refuges in a Lower Cretaceous cobble-dwelling hardground fauna". Palaeontology 29:691–703.
• Wilson, M.A. and Palmer, T.J., 2006. "Patterns and processes in the Ordovician Bioerosion Revolution". Ichnos 13: 109–112.[1]
• Yochelson, E.L. and Fedonkin, M.A., 1993. Paleobiology of Climactichnites, and Enigmatic Late Cambrian Fossil. Smithsonian Contributions to Paleobiology 74:1–74.

External links[edit]

• Encyclopaedia-style article about trace fossils
• Ichnogenus images
• Chuck D. Howell's Ichnogenera Photos
• Glossary of Ichnology Terms

What evidence is given by fossils?

How are fossils used for evidence of evolution?

What is the evidence for evolution?

How is biogeography evidence for evolution?