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Trace Fossils Divisions
Trace fossils, also called ichnofossils, are geological records of biological activity. Trace fossils may be impressions made on the substrate by an organism: for example, burrows, borings (bioerosion), footprints and feeding marks, and root cavities. 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 - or sedimentological structures produced by biological means - for example, stromatolites. Trace fossils contrast with body fossils, which are the fossilised remains of parts of organisms' bodies, usually altered by later chemical activity or mineralisation. The taxonomic classification of trace fossils parallels the taxonomic classification of organisms under the International Code of Zoological Nomenclature. In trace fossil nomenclature a Latin binominal name is used, just as in animal and plant taxonomy, with a genus and specific epithet. When talking about trace fossils the genus is called an ichnogenus, and the species is an ichnospecies. The name is similarly italicized, and in full reference the author plus the year of publication should be cited. "Ichnogenus" and "ichnospecies" are commonly abbreviated as "igen." and "isp.", respectively. The most promising cases of phylogenetic classification are those in which similar trace fossils show details complex enough to deduce the makers, such as bryozoan borings, large trilobite trace fossils such as Cruziana, and vertebrate footprints. However, most trace fossils lack sufficiently complex details to allow such classification. |
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