Trilobite systematics: the last 75 years

The progress achieved in trilobite systematics over the last 75 years is briefly reviewed. Different app genetics have influenced the way trilobites have been classified. Classical evolutionary taxonomy, the stratigraphi cladistics have all contributed in different ways to the current classification, which has evolved piecemeal, and is still some ways. Nonetheless, progress towards a phylogenetic classification has been made, especially as the result of i ontogenies provided by well-preserved silificified material. Trilobites are a well-defined clade within a larger arac Agnostida have been excluded from Trilobita, but are perhaps best considered as specialised trilobites, at least until are described. The outstanding problems in classification of each trilobite order are reviewed. Most are concerned with of the appropriate Cambrian sister taxa, and the discovery of the relevant ontogenies. It is very likely that post-Camb deeply into the Cambrian. The coherence, or otherwise, of Proetida, Asaphida, Corynexochida and the lichid/odontople be resolved by such studies. The problems of paraphyly in Ptychopariida and Redlichiina may prove more obdur brevity of certain Cambrian family ranges may be partly a taxonomic artefact. The possibility of a late Cambrian gap some clades should be considered.