Editing Trace fossil (section)

{{short description|Geological record of biological activity}}
{{about|a type of fossil|Dinosaur Footprints park in Massachusetts|Dinosaur Footprints}}
[[Image:Cheirotherium prints possibly Ticinosuchus.JPG|thumb|''[[Chirotherium]]'' footprints in a [[Triassic]] sandstone]]
{{wikt | ichnofossil}}
{{Paleontology}}
[[Image:Protichnites.jpg|thumb|upright|The trackway ''[[Protichnites]]'' from the [[Cambrian]], [[Blackberry Hill]], central [[Wisconsin]]]]

A '''trace fossil''', also called an '''ichnofossil''' ({{IPAc-en|ˈ|ɪ|k|n|oʊ|ˌ|f|ɒ|s|ᵻ|l}}; {{etymology|grc|''{{wikt-lang|grc|ἴχνος}}'' ({{grc-transl|ἴχνος}})|trace, track}}), is a [[fossil]] record of [[earliest known life forms|biological activity]] by [[lifeform]]s, but not the preserved remains of the [[organism]] itself.<ref>{{Cite web |title=GEOL 331/BSCI 333 Ichnology: The Study of Trace Fossils |url=https://www.geol.umd.edu/~tholtz/G331/lectures/331ichno.html |access-date=2024-10-25 |website=www.geol.umd.edu}}</ref> Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or by [[Mineralization (geology)|mineralization]]. The study of such trace fossils is '''ichnology''' - the work of '''ichnologists'''.<ref>{{Cite journal |last1=Pineda-Salgado |first1=Gabriela |last2=Quiroz-Barroso |first2=Sara A. |last3=Pineda-Salgado |first3=Gabriela |last4=Quiroz-Barroso |first4=Sara A. |date=2018 |title=Ichnology: modern and fossil evidence of biological activity |url=https://www.scielo.org.mx/scielo.php?pid=S1405-33222018000200001&script=sci_arttext |journal=Boletín de la Sociedad Geológica Mexicana |language=en |volume=70 |issue=2 |pages=0 |doi=10.18268/bsgm2018v70n2p1 |issn=1405-3322|doi-access=free }}</ref>

Trace fossils may consist of physical impressions made on or in the [[Substrate (marine biology)|substrate]] by an organism.<ref>{{Cite web |date=2024-02-08 |title=8.3: Trace Fossils- Studies in Scurrying, Scraping, and Slithering |url=https://geo.libretexts.org/Bookshelves/Geology/Introduction_to_Historical_Geology_(Johnson_et_al.)/08:_Taphonomy_-_The_Science_of_Death_and_Decay/8.03:_Trace_Fossils-_Studies_in_Scurrying_Scraping_and_Slithering |access-date=2024-10-25 |website=Geosciences LibreTexts |language=en}}</ref> For example, [[burrow fossil|burrow]]s, borings ([[bioerosion]]), [[urolite]]s (erosion caused by evacuation of liquid wastes), [[Ichnite|footprints]], 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 [[coprolite]]s (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 [[Morphology (biology)|appearance]] and on the implied behaviour, or [[ethology]], of their makers.