A taxonomic revision of the genus Procolophon and the phylogenetic relationships of Procolophonoid reptiles

Martinez, Juan Carlos Cisneros

A taxonomic revision of the genus Procolophon and the phylogenetic relationships of Procolophonoid reptiles

dc.contributor.author	Martinez, Juan Carlos Cisneros
dc.date.accessioned	2008-03-18T08:54:02Z
dc.date.available	2008-03-18T08:54:02Z
dc.date.issued	2008-03-18T08:54:02Z
dc.description.abstract	ABSTRACT This study presents a taxonomic revision of some procolophonoid parareptiles and a detailed, global analysis of procolophonid intrarelationships. The poorly known genus Candelaria, from the Middle Triassic of Brazil, is identified on the basis of new material as an owenettid, rather than a procolophonid as previously thought. Thus, Candelaria represents the youngest owenettid and the first member of this group from South America. The cranium of Candelaria is also remarkable for having temporal fenestrae, and the significance of this character within the Parareptilia is discussed. Based on a comprehensive review of specimens referred to different Procolophon species, it is proposed that only the type species, Procolophon trigoniceps, is valid. Thus, Procolophon specimens from Brazil, South Africa, and Antarctica are all referable to P. trigoniceps. Consequently, P. trigoniceps has one of the broadest known geographic ranges among Triassic tetrapod species. A comprehensive cladistic analysis of procolophonids more firmly resolves the relationships within that group. The analysis reveals that Procolophoninae and Leptopleuroninae are valid monophyletic groups, whereas Spondylolestinae is paraphyletic. The species formerly assigned to the genus ‘Thelegnathus’ from the Middle Triassic of South Africa, and those assigned to ‘Eumetabolodon’ from the Lower-Middle Triassic of China, are paraphyletic. The poorly known Spondylolestes from the Dicynodon Assemblage Zone of South Africa is considered valid and possibly represents the only Permian procolophonid in Gondwana. A new species, Kitchingnathus untabeni, is identified in the Lystrosaurus Assemblage Zone of South Africa. It is a basal member of the Procolophonidae and co-occurs with Procolophon in the Upper Katberg Formation. The new taxon is characterized by the presence of a large number of thin, bicuspid teeth. Character optimisation indicates that bicuspid teeth were acquired independently in K. untabeni, and hence originated twice during procolophonid evolution. A review of procolophonid records worldwide reveals a fossil hiatus for members of this group in the Ladinian and most of the Carnian.	en
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dc.identifier.uri	http://hdl.handle.net/10539/4676
dc.language.iso	en	en
dc.subject	Procolophon	en
dc.subject	parareptiles	en
dc.subject	phylogeny	en
dc.subject	Gondwana	en
dc.subject	Triassic	en
dc.title	A taxonomic revision of the genus Procolophon and the phylogenetic relationships of Procolophonoid reptiles	en
dc.type	Thesis	en