VERTEBRATE BURROWING ACTIVITIES AT THE PERMOTRIASIC TRANSITION IN SOUTHERN AFRICA

FERNANDEZ, V; ABDALA, F.; CARLSON, K.J.; GESS, R.; RUBIDGE, B. S.

Mendoza

Congreso; 4th International Paleontological Congress; 2014

The Karoo Basin of Southern Africa has provided numerous examples of vertebrate burrowing Behaviours in the strata spanning the Permo-Triassic (PT) boundary. The abundance of these underground shelters was therefore interpreted as an evidence of their importance to provide stable environments protecting their inhabitants from harsh climatic conditions consecutive to the PT mass extinction event. A few burrow diggers have been identified from fossilized burrow casts, notably cynodonts. It seemed logical to view burrowing behaviours as a key strategy to survive the extinction event. However this interpretation is weakened by the few numbers of identified burrowers compared to the numbers of burrow morphologies and sizes discovered. Secondly, an underground lifestyle was also ascertained for other taxa from older units of the basin which need to be taken into consideration in order to understand the evolution of burrowing strategy prior to the mass extinction event. Using new approaches, we investigate fossilized burrow casts, notably using X-ray tomography, to expand our knowledge on fossoriale lifestyle during this time. This technique allows us to explore the content of burrow casts, aiming to discover, and possibly identify, vertebrate remains. By keeping the sedimentological infill intact, we preserve taphonomical information, essential to discriminate taxa as burrowers or opportunistic inhabitants. In this work we present the latest results of this project, focusing on various types of burrows from different geological formations. We present a new burrow type from the Late Permian and early conclusions on the presumable burrow maker and discuss implications regarding burrowing as a survival strategy at the end of the Paleozoic.