Cryptoclidid plesiosaurs (Sauropterygia, Plesiosauria) from the Upper Jurassic of the Atacama Desert

Abstract

This study presents the first plesiosaurs recovered from the Jurassic of the Atacama Desert that are informative at the genus level. One specimen is represented by an articulated axial section that shows distinctive features, such as cervical vertebrae with oval articular facets and gracile neural pedicles. The second specimen preserves similar vertebrae, teeth, propodials, and pectoral elements. Their anatomical characteristics allow us to refer them toMuraenosaurus, a genus of cryptoclidid plesiosaur previously reported in Callovian rocks of Europe and Argentina. A third specimen is represented by a fragmentary jaw, which coincides precisely in size and anatomical features with that ofVinialesaurus caroli, another cryptoclidid plesiosaur exclusively known from the Oxfordian of Cuba. The material studied represents the first record ofMuraenosaurusin the Oxfordian of the Profeta-La Ternera Basin in northern Chile, adding to previous regional occurrences of the genus and to the record ofCryptoclidus, both also known from the Callovian of Argentina. On the other hand, the specimen referred toVinialesaurusis the first appearance of this genus in the Southern Hemisphere. These new records give strong support to the exchange of marine vertebrates between the northern Tethys and the southern Pacific through the Caribbean Seaway during the Middle and Late Jurassic.