Trace fossil classification: Difference between revisions

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{{Short description|Systems for grouping fossilised evidence odof biological activity}}

{{redirect|Ichnos|the Tony Oxley album|Ichnos (album)}}

[[Trace fossil]]s are [[Biological classification|classified]] in various ways for different purposes. Traces can be classified [[#Taxonomic classification|taxonomically]] (by morphology), [[#Ethologic classification|ethologically]] (by behavior), and [[#Toponomic classification|toponomically]], that is, according to their relationship to the surrounding sedimentary layers. Except in the rare cases where the original maker of a trace fossil can be identified with confidence, phylogenetic classification of trace fossils is an unreasonable proposition.

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* ''[[Fodinichnia]]'' are feeding traces which are formed as a result of organisms disturbing the sediment in their search for food. They are normally created by [[deposit feeder]]s as they tunnel through soft sediments, usually producing a 3D structure.

* '''''Pascichnia''''' are a different type of feeding trace for which the trophic guild responsible are [[grazing|grazer]]s. They create 2D features as they scour the surface of a hard or soft [[Substrate (biology)|substrate]] in order to obtain [[nutriment]].

* '''''Repichnia''''' are locomotory tracks that show evidence of organisms moving from one station to another, usually in a near-straight to slightly curved line. Most of the very few traces to be verifiably assigned to a specific organism are in this category, such as various [[arthropod]] and [[vertebrate]] trackways.<ref>{{cite journal |last=Seilacher |first=A. |year=1967 |title=Bathymetry of trace fossils |journal=Marine Geology |volume=5 |issue= 5–6|pages=413–428 |doi=10.1016/0025-3227(67)90051-5 |bibcode=1967MGeol...5..413S }}</ref>

===Other ethological classes===

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Since the inception of behavioural categorization, several other ethological classes have been suggested and accepted, as follows:

* ''Aedificichnia'':<ref>{{cite journal |last1=Bown |first1=T. M. |last2=Ratcliffe |first2=B. C. |year=1988 |title=The origin of ''Chubutolithes'' Ihering, ichnofossils from the Eocene and Oligocene of Chubut province, Argentina |journal=Journal of Paleontology |volume=62 |issue=2 |pages=163–167 |doi=10.1017/S0022336000029802 |bibcode=1988JPal...62..163B |s2cid=20261299 |url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1136&context=entomologypapers |url-access=subscription }}</ref> evidence of organisms building structures outside of the [[infauna]]l realm, such as [[termite]] mounds or [[wasp]] nests.

* ''Agrichnia'':<ref>Ekdale, AA; Bromley, RG; Pemberton, SG (1984) Ichnology: Trace fossils in sedimentology and stratigraphy. Society of Economic Paleontologists and Mineralogists Short Course, no 15, 317 pp.</ref> so called "gardening traces", which are systematic burrow networks designed to capture migrating [[meiofauna]] or perhaps even to culture [[bacteria]]. The organism would have continually inspected this burrow system to prey on any smaller organisms that strayed into it.

* ''Calichnia'':<ref>Genise, JF & Bown, TM (1991) New Miocene scarabaeid and hymenopterous nests and Early Miocene (Santacrucian) palaeoenvironments, Patagonian Argentina. Ichnos, 3: 107–117.</ref> structures that were created by organisms specifically for [[Reproduction|breeding]] purposes, e.g. [[bee]] cells.

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* ''Volichnia'': traces that show the position a flying organism (usually an insect) landed on a soft sediment.

Fixichnia<ref>{{cite journal |last1=Gibert |first1=J. M. de |last2=Domènech |first2=R. |last3=Martinell |first3=J. |year=2004 |title=An ethological framework for animal bioerosion trace fossils upon mineral substrates with proposal of new class, fixichnia |journal=Lethaia |volume=37 |issue=4 |pages=429–437 |doi=10.1080/00241160410002144 |bibcode=2004Letha..37..429G }}</ref> is perhaps the group with the most weight as a candidate for the next accepted ethological class, being not fully described by any of the eleven currently accepted categories. There is also potential for the three plant traces (cecidoichnia, corrosichnia and sphenoichnia) to gain recognition in coming years, with little attention having been paid to them since their proposal.<ref>{{cite journal |last=Mikuláš |first=R. |year=1999 |title=Notes on the concept of plant trace fossils related to plant-generated sedimentary structures |journal=Věštník Českého Geologického ústavu |volume=74 |issue=1 |pages=39–42 }}</ref>

==Toponomic classification==