The End-Permian mass extinction and subsequent recovery of terrestrial ecosystems in southern Gondwana

This project focuses on the terrestrial ecology of southern Gondwana during an interval of geological time that encompasses the evolutionary transitions from true reptiles to true mammals as well as the earliest dinosaurs. The primary sources of data are the rocks and fossils of the Karoo Supergroup in South Africa, Lesotho, Namibia, East Africa and Madagascar. The motivation for placing this project in this focus area is that the Karoo Basin is undoubtedly the world’s largest and richest collecting grounds for therapsids, the long extinct transitionary group between reptiles and mammals, and as such it is a truly unique South African research opportunity. The rationale for this project is to study the changes in the landscapes and terrestrial ecology of the Karoo Basin at many different time intervals, over a total timespan of some 60 million years, in order to document and calibrate the causes, rates and timing of the evolutionary innovations that eventually led to the origin of mammals and dinosaurs some 200 million years ago. Improving our knowledge of life before the advent of humans, not only helps us understand how the present day biodiversity evolved but also demonstrates its susceptibility to natural changes in the physical environments of the Earth’s surface- changes that are beyond the control of mankind.

The objectives of the following research plan are simply to find out what controls natural changes in the Earth’s terrestrial ecosysytems over time scales measured in thousands, millions and tens of millions of years using the Karoo-aged rocks and fossils as a source of information.

This is achieved mainly by detailed field-based studies of fossil- bearing strata of different ages in different parts of southern Gondwana. This proposed 4-year research plan is entirely focused on a single topic- the End-Permian Mass Extinction and subsequent biotic recovery.

Notable fossils recovered at the P-T boundary sections to date include an articulated Moschorhinus skeleton, 2 intercurled juvenile Thrinaxodon skeletons, a new cynodont currently in press named "Progalesaurus lootsbergensis", a complete skull of Dinanomodon -a rare parrot-beaked dicynodont, an amphibian with ventral scales, the largest Lystrosaurus skeleton yet excavated, bonebeds of multiple animals that died together, a rare trackway surface at the boundary both showing herbivore and carnivore footprints.  

One of the highlights of the past two years was the recovery of a skull and lower jaw of a new burnetiid from a farm near Aberdeen in the southern Karoo. This is closely related to Proburnetia which is represented by a singe specimen found in northern Russia!. Prof Bruce Rubidge (BPI Wits) is helping with the type description and a discussion of tetrapod migration patterns in Pangaea during the latest Permian and this paper has been submitted for publication. A new captorhinomorph was recovered by Dr Sean Modesto (Carnegie Museum, Pittsburg) from the Leeuwkloof taphonomic study section near Beaufort West. This has since been prepared and described. Another publication on the sexual dimorphism of Diictodon (in collaboration with Prof Reisz and Dr Sullivan of Toronto Univ) has shown that adult males supported tusks whereas the females were tuskless. Corwin Sullivan's PhD research on the functional anatomy of Diictodon relied heavily on data and specimens collected from this study. This project has now amassed what is probably the worlds largest collection of therapsid coprolites. Around 60 thin sections have been cut and work is progressing with analysing their composition with special attention to possible hair like structures and the fragmentation patterns of bones in these ancient faeces.