Abstract
The end-Permian mass extinction of marine invertebrates and non-marine tetrapods is examined. Fauna!, lithostratigraphical and geochemical data indicate that the mass extinction was a prolonged, gradual event, and was not initiated or accelerated by a catastrophic mechanism. The cause of the greatest ever reduction in Phanerozoic life isnot obvious, however, the taxa affected and the timing of their extinction, in both realms, suggests that global cooling, with associated regressions of warm shallow seas, played a significant role.
Comparison of six data bases for fossil tetrapods, spanning 100 years, illustrates the improvements in our knowledge of the tetrapod fossil record over that time. Recent improvements have resulted from re-evaluations of taxonomy and stratigraphy, and not just from the discovery of new fossils.
The scant information available on the inter-relationships of pareiasaurs is reviewed. A cladistic analysis of 12 pareiasaurian taxa reveals that Elginia is the most specialised member of the group and is most closely related to Scutosaurus, Nanoparia and Pareiasuchus. An attempt is made to establish the migration routes of pareiasaurs, based on
stratigraphic, fauna! and palaeogeographical data.
Only two specimens of Elginia are known. A restoration of the skull and skeleton of Elginia is attempted, based on the type skull, BGSE 4783-4788, and the paratype skeleton, RSM 1956. 8.1. The paratype skull is figured for the first time, and the paratype skeleton is described and figured for the first time.
Elginia was probably a herbivore, feeding on soft vegetation with weak, multi-cusped teeth. The remarkable spinosity of the skull and the well-structured body armour may have constituted a defence mechanism against predators.
| Date of Award | Jul 1991 |
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| Original language | English |
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