Abstract：
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.
摘要：
Saurotterygians是中生代海洋爬行动物的地层范围最长的进化枝，其全球化石记录跨越约1.8亿年1。然而,它们的早期进化只有从现在的北半球才知道，在晚三叠纪（晚期Olenekian，~2.488亿年前[Ma]2)，andviapossibletrans-Arcticmigration1totheEasternPanthalassasuper-oceanpriortothelarestmiddleTriasic(Olenekian-larestAnisian3,4,hu247Ma).这里,我们描述了来自南半球的地质最古老的出海爬行动物-来自中三叠纪（Anisian，在新西兰的246Ma6之后)。因此，按时间缩放的祖先范围估计揭示了来自北部特提斯起源中心的意外的圆形冈瓦南高古纬度（>60°S7）扩散。这与二叠纪末物种大灭绝8后的沙龙的适应性多样化相吻合，并表明迅速的全球化伴随着它们在最早的中生代的初始辐射。
