Johan Lindgren

Plesiosaurs are secondarily aquatic reptiles with a fossil record that extends for over 140 million years, and their remains have been found in localities representing 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 articularly long-necked forms is anything but a straightforward task. Moreover, animals with such an oddly-shaped body are unlikely to survive in coldwater 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 approach) 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 endeavours show that an insulating blubber layer must have been present to assure a suitable temperature distribution within the plesiosaur body when it inhabited cold water regions.