A new elasmosaurid from the upper Maastrichtian López de Bertodano Formation: new data on weddellonectian diversity

O?GORMAN, JOSÉ P.; PANZERI, KAREN M.; FERNÁNDEZ, MARTA S.; SANTILLANA, SERGIO; MOLY, JUAN J.; REGUERO, MARCELO

ALCHERINGA

TAYLOR & FRANCIS LTD

Año: 2017 p. 1 - 12

0311-5518

Elasmosaurids are one of the most frequently recorded marine reptiles from the Weddellian Province (Patagonia, Western Antarctica and NewZealand). Improvements in our knowledge of elasmosaurid diversity have been problematic because of their conservative postcranial morphology.However, recent studies have helped to improved our understanding of the diversity of this group. Here, a new elasmosaurid specimen from theupper Maatrichtian horizons of the López de Bertodano Formation, Antarctica, MLP 14-I-20-16, is described. MLP 14-I-20-16 is one of the youngestnon-aristonectine weddellonectian elasmosaurids from Antarctica. We confirm the coexistence of aristonectine and non-aristonectine elasmosauridsin Antarctica until the end of the Cretaceous. MLP 14-I-20-16 shows distinctive short and broad posterior cervical vertebrae, a featureonly shared among the weddellonectian elasmosaurids by the Maastrichtian Morenosaurus stocki, although the same vertebral proportions are alsorecorded for the giant Cenomanian elasmosaurids Thalassomedon haningtoni. Comparison between MLP 14-I-20-16 and other elasmosaurids fromthe Maastrichtian of Antarctica indicates that at least two different non-aristonectine elasmosaurids were present in Antarctica during the lateMaastrichtian.