Oldest southern sauropterygian reveals early marine reptile globalization

• Published in: Current Biology
• Main Authors: Kear, Benjamin P., Roberts, Aubrey J., Young, George, Terezow, Marianna, Mantle, Daniel J., Barros, Isaias Santos, Hurum, John H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Uppsala universitet, Evolutionsmuseet 2024
• Subjects: Ecology; Ekologi; Arctic; New Zealand
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-536186; https://doi.org/10.1016/j.cub.2024.03.035

Sauropterygians were the stratigraphically longest-ranging clade of Mesozoic marine reptiles with a global fossil record spanning ∼180 million years1. 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-ocean1 after the late-Early Triassic (late Olenekian, ∼248.8 million years [Ma] ago2), and via possible trans-Arctic migration1 to the Eastern Panthalassa super-ocean prior to the earliest Middle Triassic (Olenekian–earliest Anisian3,4, ∼247 Ma). Here, we describe the geologically oldest sea-going reptile from the Southern Hemisphere — a nothosaur (basal sauropterygian5) 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 extinction8 and suggests that rapid globalization accompanied their initial radiation in the earliest Mesozoic.