Mesozoic marine reptile palaeobiogeography in response to drifting plates

Abstract

During the Mesozoic, various groups of reptiles underwent a spectacular return to an aquatic life, colonizing most marine environments. They were highly diversified both systematically and ecologically, and most were the largest top-predators of the marine ecosystems of their time. The main groups were Ichthyosauria, Sauropterygia, Thalattosauria, and several lineages of Testudinata, Crocodyliformes, Rhynchocephalia and Squamata. Here we show that the palaeobiogeographical distribution of these marine reptiles closely followed the break-up of the supercontinent Pangaea and that they globally used the main marine corridors However, if large faunal interchanges were possible at a global scale following a dispersal model, some provinces, such as the Mediterranean Tethys, were characterized by a peculiar faunal identity, illustrating an absence of migration with time despite the apparent lack of barriers. So, if Continental Drift enabled global circulations and faunal interchanges via dispersals among Mesozoic marine reptiles, others parameters, such as ecological and biological constraints, probably also played a role in the local endemic distribution of some of these marine groups, as they do today.

Foramina in plesiosaur cervical centra indicate a specialized vascular system

“…Also, the ability of deep diving (see above) is an adaptation to the pelagic habitat because prey there is sparser and more evenly distributed across the water column (and not at the sea bottom) than in coastal habitats. Plesiosaurians show all these features of adaptation to a pelagic habitat and not surprisingly are globally distributed at least by the Middle Jurassic (Bardet et al, 2014).…”

Ichthyosaurs from the French Rhaetian indicate a severe turnover across the Triassic–Jurassic boundary

“…Only a handful of marine reptile occurrences have been reported in Rhaetian strata (see for example, the compilations of Bardet et al 2014;Kelley et al 2014). Besides the scarce material reported from southern France, Austria, and England (Corroy 1933;Zapfe 1976;Storrs 1994), Sauvage ( , 1883 described abundant reptilian material and several new taxa from the 'Pellat' and 'Dumortier' collections, originating from latest Triassic strata in the Autun area, eastern France.…”

Ecomorphological diversifications of Mesozoic marine reptiles: the roles of ecological opportunity and extinction

“…Such opportunities are the primary catalysts for bursts of phenotypic evolution and adaptive radiation (Simpson 1953;Yoder et al 2010). Mesozoic marine reptiles are a polyphyletic assemblage, made up of species from independent evolutionary invasions of the marine realm from different parts of the neodiapsid tree (Bardet et al 2014). …”

“…Sauropterygians and ichthyosauromorphs differ from mosasauroids and thalattosuchians in terms of evolutionary duration and terrestrial phylogenetic heritage. Thalattosuchians and mosasauroids represent shorter-lived and specialized offshoots from large, ancestrally terrestrial, clades (Bardet et al 2014). On the other hand, ichthyosauromorphs and sauropterygians were long-lived marine clades, and their evolution was punctuated by major phylogenetic bottlenecks in the Late Triassic (Thorne et al 2011).…”