Growth strategies of the earliest crocodilians.

Crocodilians and their closest living relatives appeared in the Late Triassic. Major questions still remain about the growth strategies and tissues of these ancient crocodilians. Answering these questions is key for understanding the evolutionary history of living crocodilians and requires sampling broadly across fossil crocodilians using osteohistological methods. A challenge for this line of research is that classical osteohistology requires destructive sampling, and early crocodylomorphs are rare components of the fossil record. Synchrotron microtomography offers a non-destructive alternative to destructive approaches and has already shown great promise in imaging internal bone microstructures. In this study, we propose to use PPC-SRμCT at submicron voxel size to image osteohistological cross sections of the long bones of four key fossil species from South Africa. This study builds a framework for understanding growth strategies across Crocodylomoprha and other vertebrate clades.