Systematics and evolutionary history of proterosuchian archosauriforms

Ezcurra, Martin D. (2015). Systematics and evolutionary history of proterosuchian archosauriforms. University of Birmingham. Ph.D.

Preview

Ezcurra15PhD.pdf
PDF - Accepted Version
Download (16MB)

Abstract

The evolutionary history of archosauromorphs is of particular interest because it includes the origins of two of the best-known and most distinctive extant tetrapod groups: crocodylians and birds. In this thesis, the anatomy, taxonomy and systematics of the Permo-Triassic non-archosaur archosauromorphs are revised. A revision of the Permo-Triassic archosauromorph record indicates that only four Permian species are known and there are three valid proterosuchid species immediately after the Permo-Triassic boundary in South Africa. Analyses of cranial ontogenetic variation in \(Proterosuchus\) \(fergusi\) found that ontogenetic modification events (e.g. heterochrony) may have been key drivers of the evolution of the general shape of the skull at the base of Archosauriformes. A comprehensive quantitative phylogenetic analysis recovered a polyphyletic “Prolacertiformes”, restricted the taxonomic content of Proterosuchidae to only six species, Erythrosuchidae was composed of eight nominal species, and \(Euparkeria\) \(capensis\) was found as the sister-taxon of the clade that includes proterochampsians (doswelliids + proterochampsids) and archosaurs. The results obtained here suggest that the evolutionary history of the archosauriforms during the Early Triassic can be subdivided into a first phase characterized by the short-lived “disaster-clade” Proterosuchidae and a second phase that witnessed the initial morphological and probably palaeoecological diversification of the group.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):