Oldest southern sauropterygian reveals early marine reptile globalization

This is the authors' abstract. We don't add key points for this paper.

Sauropterygians were the stratigraphically longest-ranging clade of Mesozoic marine reptiles with a global fossil record spanning ∼180 million years1Bardet N. Falconnet J. Fischer V. Houssaye A. Jouve S. Pereda Suberbiola X. Perez-García A. Rage J.-C. Vincent P. Mesozoic marine reptile palaeobiogeography in response to drifting plates.Gond. Res. 2014; 26: 869-887Crossref Scopus (0) Google Scholar. However, their early evolution has only been known from what is now the Northern Hemisphere, extending across the northern and trans-equatorial western margins of the Tethys paleo-ocean1Bardet N. Falconnet J. Fischer V. Houssaye A. Jouve S. Pereda Suberbiola X. Perez-García A. Rage J.-C. Vincent P. Mesozoic marine reptile palaeobiogeography in response to drifting plates.Gond. Res. 2014; 26: 869-887Crossref Scopus (0) Google Scholar after the late-Early Triassic (late Olenekian, ∼248.8 million years [Ma] ago2Jiang D.Y. Zhou M. Motani R. Tintori A. Fraser N.C. Huang J.D. Rieppel O. Ji C. Fu W.L. Sun Z.Y. Lu H. Emergence and ecological transition of the Mesozoic marine reptiles: Evidence from the Early Triassic Chaohu and the Middle Triassic Xingyi Faunas.Palaeogeogr. Palaeoclimatol. Palaeoecol. 2023; 628111750Crossref Scopus (2) Google Scholar), and via possible trans-Arctic migration1Bardet N. Falconnet J. Fischer V. Houssaye A. Jouve S. Pereda Suberbiola X. Perez-García A. Rage J.-C. Vincent P. Mesozoic marine reptile palaeobiogeography in response to drifting plates.Gond. Res. 2014; 26: 869-887Crossref Scopus (0) Google Scholar to the Eastern Panthalassa super-ocean prior to the earliest Middle Triassic (Olenekian–earliest Anisian3Lovelace D.M. Doebbert A.C. A new age constraint for the Early Triassic Alcova Limestone (Chugwater Group), Wyoming.Palaeogeogr. Palaeoclimatol. Palaeoecol. 2015; 424: 1-5Crossref Scopus (12) Google Scholar,4Scheyer T.M. Neuman A.G. Brinkman D.B. A large marine eosauropterygian reptile with affinities to nothosauroid diapsids from the Early Triassic of British Columbia, Canada.Acta Palaeontol. Pol. 2019; 64: 745-755Crossref Scopus (9) Google Scholar, ∼247 Ma). Here, we describe the geologically oldest sea-going reptile from the Southern Hemisphere — a nothosaur (basal sauropterygian5Rieppel O. Sauropterygia I: Placodontia, Pachypleurosauria, Nothosauroidea, Pistosauroidea. Handbook of Paleoherpetology. 12A. Verlag Dr Friedrich Pfeil, München2000Google Scholar) from the Middle Triassic (Anisian, after ∼246 Ma6) of New Zealand. Time-scaled ancestral range estimations thus reveal an unexpected circum-Gondwanan high-paleolatitude (>60° S7) dispersal from a northern Tethyan origination center. This coincides with the adaptive diversification of sauropterygians after the end-Permian mass extinction8Wang W. Shang Q. Cheng L. Wu X.C. Li C. Ancestral body plan and adaptive radiation of sauropterygian marine reptiles.iScience. 2022; 25105635Abstract Full Text Full Text PDF Scopus (6) Google Scholar and suggests that rapid globalization accompanied their initial radiation in the earliest Mesozoic.