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

Abstract

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 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.http://zoobank.org/urn:lsid:zoobank.org:pub:1B9D10DA-0373-41B5-BFFF-E7AC25D79BF3

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

ACKNOWLEDGMENTS

This research was supported by projects PICT 2008-0261, PICT 2012-0748, PICTO 2010-0093, UNLP N 677, and UNLP N607. The authors thank Z. Gasparini for reading an earlier version of the manuscript, N. Hiller for comments that improved the English grammar, and M. Reguero, J. Martin, J. Moly, and A. Concheyro for their Antarctic field work and comments that improved the manuscript. The authors also thank the work of two anonymous reviewers and R. O’Keefe for comments that improved the manuscript. This contribution would have not been possible without logistic support from the Instituto Antártico Argentino (Buenos Aires) and the Fuerza Aérea Argentina. E. Fordyce (Otago University), P. Scofield (Canterbury Museum), and J. Simes (National Paleontology Collection, GNS Science Avalon) allowed us to review the elasmosaurs from those institutions. We also thank N. Hiller for help during the revision of some specimens from Canterbury Museum. Thanks to L. Acosta Burllaile for the preparation of some elements and B. Pianzola for taking some of the photographs.