CFD modelling of the thermo- and hydrodynamic capabilities of long-necked plesiosaurs (Sauropterygia, Elasmosauridae)

Abstract

Plesiosaurs are secondarily aquatic reptiles with a fossil record extending over 140 million years, and their fossilised remains have been found in sediments deposited in both warm, equatorial waters and cold, high-latitude environments. They are usually portrayed as a snake threaded through the body of a sea turtle. However, due to a general absence of preserved soft tissues, reconstructing the life appearance of particularly long-necked forms is anything but a straightforward task. Moreover, animals with such an oddly-shaped body form are unlikely to survive in cold-water environments. To investigate the ability of these ancient marine reptiles to inhabit high-latitude waters, we examined the heat transfer in two virtually reconstructed plesiosaurs: one built according to conventional wisdom (i.e., with a long and narrow neck) and one equipped with a peripheral layer of insulating blubber. We compared several modelling approaches (gradually increasing the complexity of our virtual reconstructions) to assess their pros and cons. We also investigated the temperature distribution within the two body types and tested their hydrodynamic performance by simulating a cruising plesiosaur at a steady velocity. The results of our endeavors show that insulating blubber must have been present to assure a suitable temperature distribution within the plesiosaur body when it inhabited cold water regions.