The first skeletal evidence of a dicynodont from the lower Elliot Formation of South Africa
Date
2018
Authors
Kammerer, Christian F.
Journal Title
Journal ISSN
Volume Title
Publisher
Evolutionary Studies Institute
Abstract
Historical fossil specimens from the lower Elliot Formation are identified as representing a large-bodied dicynodont, the first known
from skeletal material in the Late Triassic of South Africa. Although fragmentary, these fossils differ from all other known Triassic
dicynodonts and are here described as a new taxon, Pentasaurus goggai gen. et sp. nov. Pentasaurus can be distinguished from other
Triassic dicynodonts by a number of mandibular characters, most importantly the well-developed, unusually anteriorly-positioned
lateral dentary shelf. Phylogenetic analysis indicates that Pentasaurus is a placeriine stahleckeriid. Placeriines include the latestsurviving
dicynodonts but their remains are primarily known from the Northern Hemisphere, with their only previously-known
Southern Hemisphere representative being the Middle Triassic Zambian taxon Zambiasaurus. The discovery of a placeriine in the Late
Triassic of SouthAfrica supports recent proposals that local climatic conditions, not broad-scale biogeographic patterns, best explain the
observed distribution of Triassic tetrapods. The tetrapod fauna of the lower Elliot Formation is highly unusual among Triassic assemblages
in combining ‘relictual’ taxa like dicynodonts and gomphodont cynodonts with abundant, diverse sauropodomorph dinosaurs.
Description
Keywords
Synapsida, Therapsida, Dicynodontia, Triassic, Karoo Basin, biogeography