Trace fossil classification

Trace fossils are classified in various ways for different purposes. Traces can be classified taxonomically (by morphology), ethologically (by behavior), and 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.

Taxonomic classification

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 binomial name is used, just as in animal and plant taxonomy, with a genus and specific epithet. However, the binomial names are not linked to an organism, but rather just a trace fossil. This is due to the rarity of association between a trace fossil and a specific organism or group of organisms. Trace fossils are therefore included in an ichnotaxon separate from Linnaean taxonomy. When referring to trace fossils, the terms ichnogenus and ichnospecies parallel genus and species 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.

Ethologic classification

The Seilacherian System

Sponge borings (Entobia) and encrusters on a modern bivalve shell, North Carolina; an example of Domichnia.

Adolf Seilacher was the first to propose a broadly accepted ethological basis for trace fossil classification.[1][2] He recognized that most trace fossils are created by animals in one of five main behavioural activities, and named them accordingly:

Other ethological classes

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

Over the years several other behavioural groups have been proposed, but in general they have been quickly discarded by the ichnological community. Some of the failed proposals are listed below, with a brief description.

Fixichnia[10] 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.[11]

Toponomic classification

Another way to classify trace fossils is to look at their relation to the sediment of origin. Martinsson[12] has provided the most widely accepted of such systems, identifying four distinct classes for traces to be separated in this regard:

Other classifications have been proposed,[2][13][14] but none stray far from the above.


Early paleontologists originally classified many burrow fossils as the remains of marine algae, as is apparent in ichnogenera named with the -phycus suffix. Alfred Gabriel Nathorst and Joseph F. James both controversially challenged this incorrect classification, suggesting the reinterpretation of many "algae" as marine invertebrate trace fossils.[15]

Several attempts to classify trace fossils have been made throughout the history of paleontology. In 1844, Edward Hitchcock proposed two orders: Apodichnites, including footless trails, and Polypodichnites, including trails of organisms with more than four feet.[15]

See also


  1. Seilacher, A (1953) Studien zur paläontologie: 1. Über die methoden der palichnologie. Neues Jahrbuch fur Geologie und Paläontologie, Abhandlungen 96: 421-452.
  2. 1 2 Seilacher, A (1964) Sedimentological classification and nomenclature of trace fossils. Sedimentology 3: 253-256. doi:10.1111/j.1365-3091.1964.tb00464.x
  3. Seilacher, A (1967) Bathymetry of trace fossils. Marine Geology 5: 413-428.
  4. Bown, TM; Ratcliffe, BC (1988) The origin of Chubutolithes Ihering, ichnofossils from the Eocene and Oligocene of Chubut province, Argentina. Journal of Paleontology 62: 163-167.
  5. 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.
  6. Genise, JF & Bown, TM (1991) New Miocene scarabaeid and hymenopterous nests and Early Miocene (Santacrucian) palaeoenvironments, Patagonian Argentina. Ichnos, 3: 107–117.
  7. Bromley, RG (1990) Trace fossils: biology and taphonomy. Unwin Hyman Ltd, London, 280 pp.
  8. Simpson, S (1975) The morphological classification of trace fossils. In Frey, RW (ed.) The study of trace fossils. New York, Springer-Verlag, pp 39-54.
  9. Ekdale, AA (1985) Palaeoecology of the marine endobenthos. Palaeogeography, Palaeoecology, Palaeoclimatology 50: 63-81.
  10. Gibert, JM de, Domènech, R & Martinell, J (2004) An ethological framework for animal bioerosion trace fossils upon mineral substrates with proposal of new class, fixichnia. Lethaia 37 (4): 429-437.
  11. Mikuláš, R (1999) Notes on the concept of plant trace fossils related to plant-generated sedimentary structures. Věštník Českého geologického ústavu 74: 39-42.
  12. Martinsson, A (1970) Toponomy of trace fossils. In Crimes, TP & Harper, JC (eds.) (1970) Trace fossils. Geological Journal, Special Issue 3: 323-330.
  13. Chamberlain, CK (1971) Morphology and ethology of trace fossils from the Ouachita Mountains, southeast Oklahoma. Journal of Paleontology, 45: 212-246.
  14. Simpson, S (1957) On the trace fossil Chondrites. Quarterly Journal, Geological Society of London 112: 475-99.
  15. 1 2 Häntzschel, Walter (1975). Moore, Raymond C., ed. Miscellanea: Supplement 1, Trace Fossils and Problematica. Treatise on Invertebrate Paleontology. Geological Society of America. ISBN 9780813730271.

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