Vegasaurus molyi, gen. et sp. nov. (Plesiosauria, Elasmosauridae), from the Cape Lamb Member (lower Maastrichtian) of the Snow Hill Island Formation, Vega Island, Antarctica, and remarks on Wedellian Elasmosauridae,

O´GORMAN, J.P.; SALGADO, L.; OLIVERO, E. B.; MARENSSI, S. A.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2015

0272-4634

ABSTRACT?A new elasmosaurid, Vegasaurus molyi, gen. et sp. nov., from Vega Island, James Ross Archipelago,Antarctica, is described. The holotype and only specimen of this species (MLP 93-I-5-1) was collected from the lowerMaastrichtian Cape Lamb Member of the Snow Hill Island Formation. Vegasaurus molyi is the only Antarctic elasmosauridand one of only a few Late Cretaceous elasmosaurids from the Southern Hemisphere whose postcranial anatomy is wellknown. Vegasaurus molyi is distinguished from other elasmosaurids by the following combination of characters: cervicalregion with 54 vertebrae with elongated centra, dumbbell-shaped articular faces and lateral ridge present in the anterior andmiddle parts of the neck but absent in the posterior-most cervical vertebrae; scapula with ventral ramus bearing a strongridge in the anteromedial corner of its dorsal surface; ilium shaft with expanded distal end, divided into two parts forming anangle of 140 opening anteriorly; and humerus with anterior knee and prominent posterior projection with accessoryposterior articular facet. Preliminary phylogenetic analysis places V. molyi within a clade that includes the Late CretaceousWedellian aristonectine elasmosaurids, Aristonectes and Kaiwhekea. This indicates a close relationship betweenAristonectinae and non-Aristonectinae Late Cretaceous Weddellian elasmosaurids and suggests a Weddellian origin for theAristonectinae.