TRILOBITE SYSTEMATICS: THE LAST 75 YEARS

The progress achieved in trilobite systematics over the last 75 years is briefly reviewed. Different approaches to phylogenetics have influenced the way trilobites have been classified. Classical evolutionary taxonomy, the stratigraphical approach, and cladistics have all contributed in different wa...

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Bibliographic Details
Published in:Journal of paleontology 2001-11, Vol.75 (6), p.1141-1151
Main Author: FORTEY, RICHARD A
Format: Article
Language:English
Subjects:
Arthropoda
biologic evolution
Cambrian
Cladistics
Classification
Evolution
Fossils
Genera
Geology
history
Invertebrata
invertebrate
Invertebrates
Larvae
morphology
Ontogeny
Paleontology
Paleozoic
Phylogenetics
phylogeny
SPECIAL 75TH ANNIVERSARY ISSUE
Systematics
Taxa
taxonomy
Trilobita
Trilobitomorpha
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Summary:The progress achieved in trilobite systematics over the last 75 years is briefly reviewed. Different approaches to phylogenetics have influenced the way trilobites have been classified. Classical evolutionary taxonomy, the stratigraphical approach, and cladistics have all contributed in different ways to the current classification, which has evolved piecemeal, and is still unsatisfactory is some ways. Nonetheless, progress towards a phylogenetic classification has been made, especially as the result of information from ontogenies provided by well-preserved silificified material. Trilobites are a well-defined clade within a larger arachnomorph group. Agnostida have been excluded from Trilobita, but are perhaps best considered as specialised trilobites, at least until limbs of eodiscids are described. The outstanding problems in classification of each trilobite order are reviewed. Most are concerned with the recognition of the appropriate Cambrian sister taxa, and the discovery of the relevant ontogenies. It is very likely that post-Cambrian clades "root" deeply into the Cambrian. The coherence, or otherwise, of Proetida, Asaphida, Corynexochida and the lichid/odontopleurid groups will be resolved by such studies. The problems of paraphyly in Ptychopariida and Redlichiina may prove more obdurate. The temporal brevity of certain Cambrian family ranges may be partly a taxonomic artefact. The possibility of a late Cambrian gap in the record on some clades should be considered.
ISSN:0022-3360
1937-2337
DOI:10.1666/0022-3360(2001)075<1141:TSTLY>2.0.CO;2