GEOL 331 Invertebrate Paleontology

Fall Semester 2004
Trace Fossils

Ichnology: Study of trace fossils (biogenic sedimentary structures)

Ichnofabric & bioturbation: degree of overturning of sediment by organisms. Excessive biological activity obliterates individual trace fossils and sedimentary structures, mixing layers, etc.

Ichnotaxonomy: by tradition, individual trace fossil forms are given "ichnogenus" and "ichnospecies" (and "ichnofamily" and so on) names, even though they do NOT in reality represent a nested hiearchy based on patterns of descent!! Two trace fossils represent the same ichnospecies if they are identical in form regardless of whether they are made by the same species or different species; additionally, the same species can produce many different ichnospecies depending on its behavior, the substrate, etc.

Other Ichnonomenclature:

Terrestrial trace fossils:
Both arthropod and vertebrate trackways are common. Unlike marine ichnofossils, repichnia dominate by orders of magnitude. However, some domichnia present:

Also, feeding traces can be found as bite marks on bones or leaves, and there are the occasional resting tracks.

Additionally, considerable study of corpolites, and eggs and nests.

Some aspects of terrestrial (primarily vertebrate (primarily locomotory)) ichnology:

Pliocene hominin tracks from Laetoli, Kenya.

Juassic pterosaur ptracks from Crayssac, France.

An important thing to remember is that an ichnite is the fossil of the animal while alive, not after it was dead!

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