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Polycotylid plesiosaur from Upper Cretaceous of Antarctica

Ben Creisler

A new paper:

Fernando E. Novas, Julia S. D'Angelo, José P. O'Gorman, Federico L.
Agnolín, Juan M. Lirio & Marcelo P. Isasi (2015)
First record of Polycotylidae (Sauropterygia, plesiosauria) from the
Upper Cretaceous of Antarctica.
Cretaceous Research 56: 563–568

In the present paper we report the incomplete skeleton of an
indeterminate polycotylid that includes the articulated pelvic girdle.
The material was collected from the Alpha Member of the Santa Marta
Formation (upper Coniacian–lower Campanian) on James Ross Island,
Antarctic Peninsula. The specimen is referred to the Polycotylidae on
the basis of its very elongate ischia and rimmed anterior and
posterior articular surfaces of the dorsal vertebrae. Additionally,
the caudal vertebrae show confluent parapophyses and neural arch
facets. The present report constitutes the first record for
polycotylids in Antarctica, being an important addition to the fossil
marine reptile diversity. Polycotylids are a scarce component of the
Weddellian herpetofauna, which are dominated by aristonectine and
non–aristonectine elasmosaurids. In contrast, in Northern Hemisphere
assemblages, polycotylids are an important component of the plesiosaur
diversity. The scarcity of polycotylids may constitute another
distinctive feature of Weddellian plesiosaur faunas.