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Vegasaurus, new elasmosaurid plesiosaur from Cretaceous of Antarctica

Ben Creisler

A new online paper:

José P. O’Gorman, Leonardo Salgado, Eduardo B. Olivero & Sergio A.
Marenssi (2015)
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
Journal of Vertebrate Paleontology (advance online publication)

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 lower Maastrichtian Cape Lamb Member of the Snow Hill Island
Formation. Vegasaurus molyi is the only Antarctic elasmosaurid and one
of only a few Late Cretaceous elasmosaurids from the Southern
Hemisphere whose postcranial anatomy is well known. Vegasaurus molyi
is distinguished from other elasmosaurids by the following combination
of characters: cervical region with 54 vertebrae with elongated
centra, dumbbell-shaped articular faces and lateral ridge present in
the anterior and middle parts of the neck but absent in the
posterior-most cervical vertebrae; scapula with ventral ramus bearing
a strong ridge in the anteromedial corner of its dorsal surface; ilium
shaft with expanded distal end, divided into two parts forming an
angle of 140° opening anteriorly; and humerus with anterior knee and
prominent posterior projection with accessory posterior articular
facet. Preliminary phylogenetic analysis places V. molyi within a
clade that includes the Late Cretaceous Wedellian aristonectine
elasmosaurids, Aristonectes and Kaiwhekea. This indicates a close
relationship between Aristonectinae and non-Aristonectinae Late
Cretaceous Weddellian elasmosaurids and suggests a Weddellian origin
for the Aristonectinae.