PhD Exit Seminar: How to Build a Better Monster: Geometric morphometric and finite element analysis of the mekosuchine crocodile forelimb to assess locomotion

Event type: 
20 June 2019

UNSW Central Lecture Block, Theatre 3

Michael Stein
Professor Sue Hand

The focus of evolutionary biomechanics is to relate form to evolutionary function in the context of physical restraint. A morphological shift in the fossil record would therefore indicate a concomitant shift in ecological condition. Mekosuchine crocodiles (Crocodylidae, Mekosuchinae) of Oligo-Miocene Australia display departures from the typical eusuchian body-plan both in the cranium and postcranium. Results from previous qualitative studies suggest these crocodiles had a more terrestrial habitus compared with modern crocodylians, yet the full capacity of mekosuchine locomotion remains to be tested. We apply a quantitative approach to mekosuchine biomechanics using both geomorphic morphometric and finite element methods, to examine the unusual morphology of the mekosuchine humerus observed in specimens available from northern Queensland and the Northern Territory and estimate the locomotory stresses engendered by it. The results indicate differences in the geometry of the diaphysis between the modern freshwater crocodiles and mekosuchines along with different patterns of structural stresses between models that simulate sprawling and high-walk gaits. Our results lend quantitative support to the terrestrial habitus hypothesis and suggest behavioural adaptations for burrowing in late Plio–Pleistocene mekosuchines.

Bio: Michael Stein has just completed his PHD at UNSW, having undertaken his undergraduate studies in genetics at University of Queensland and paleontology masters at Macquarie University. His thesis focused on the evolution of locomotion Australian Mekosuchine crocodiles through the Cenozoic. More broadly, his interests center on evolutionary plasticity and the ability of faunal elements to shift between ecological niches.