More thoughts on the new Poposaurus skull (Fig. 1) that we looked at earlier (since modified). Slightly raising the broken maxilla ascending process puts a new spin on the possibilities for the skull shape and brings it into line with multi-documented sister taxa like Lotosaurus and Shuvosaurus.
The teeth are indeed sharp. Parker and Nesbitt 2013 described them as belonging to a hyper-carnivore. But in the large reptile tree Poposaurus nests with beaked herbivores. In the fossil the teeth really don’t descend very much beyond the jawline. They are deeply rooted and triangular, not long and recurved.
Earlier we noted the less than trenchant claws on the forelimb, more appropriate for an herbivore than a carnivore. The cervicals are quite robust, able to handle a taller skull. The new reconstruction, with a possible raised maxilla ascending process, opens the possibility of a taller skull with a larger orbit, also more like an herbivore and more like its sisters.
At this point it’s just best to explore possibilities, some indicated by phylogenetic bracketing. That skull remains quite incomplete.
Gauthier JA, Nesbitt SJ, Schachner ER, Bever GS and Joyce WG 2011. The bipedal stem crocodilian Poposaurus gracilis: inferring function in fossils and innovation in archosaur locomotion. Bulletin of the Peabody Museum of Natural History 52:107-126.
Mehl MG 1915. Poposaurus gracilis, a new reptile from the Triassic of Wyoming. Journal of Geology 23:516–522.
Parker WG and Nesbitt 2013. Cranial remains of Poposaurus gracilis (Pseudosuchia: Poposauroidea) from the Upper Triassic, the distribution of the taxon, and its implications for poposauroid evolution. Geological Society, London, Special Publications 379: 22 pp.