Heritage Cases

The question of the origin of endothermy (the capacity to produce own body heat) in the therapsids has been debated for several decades. Various approaches to answer the question have been tried by numerous researchers. However, there is still no consensus on when endothermy first appeared in the therapsids, and which groups were endothermic. Several studies have shown that cynodonts and also dicynodonts possibly had an elevated thermometabolism but the time of acquisition of still unsure. While the cynodont group is under study, this project is focusing on the other therapsid groups. This proposal is a logical continuation of the research focus of the Evolutionary Studies Institute on origin of thermoregulation in the different therapsids groups. The collection of tetrapod fossils at the ESI offer a unique opportunity to analyse oxygen stable isotope compositions of apatite phosphate and carbonate (δ18Op, δ18Oc) from vertebrate teeth and bones to specifically target their ecological and thermophysiological differences. Because of the very large sample size of various tetrapods, collected by the ESI over Permo-Triassic boundary, teeth and bones are planned to be sampled from several non-cynodont species and the co-existing fauna over this boundary. For each specimen, the apatite is sampled (~40mg/sample) from the root to apex of a tooth or on the dense part of a bone. This will be divided for two analyses: - δ18Op from the phosphate group of the apatite, very robust to alteration, allows estimation of different parameters and in our case it will specifically allow interpretations on body temperature. - δ18Oc from carbonate group of the apatite. The carbonate δ18O values are compared to those from the phosphate to determine if the signal is original. As is evident from the photographs supplied we have chosen only fossils with broken bones and teeth.