A new elasmosaurid specimen from the upper Maastrichtian of Antarctica: new evidence of a monophyletic group of Weddellian elasmosaurids

Abstract

O’Gorman, J.P. & Coria, R.A. September 2016. A new elasmosaurid specimen from the upper Maastrichtian of Antarctica: new evidence of a monophyletic group of Weddellian elasmosaurids. Alcheringa 41, xxx–xxx. ISSN 0311-5518

A new fossil elasmosaurid specimen, MLP 15-I-7-48, from the upper Maastrichtian Sandwich Bluff Member of the López de Bertodano Formation, Vega Island, Archipelago James Ross, Antarctica, is described. The fossil is a well-preserved anterior limb, which shares with Vegasaurus molyi from the upper Maastrichtian of Antarctica, a concave to flat anterior margin of the humeral shaft, and with Vegasaurus molyi and Aphrosaurus furlongi from the upper Maastrichtian of California, a well-defined depression on the anterior margin of the ventral surface of the humeral shaft. A phylogenetic analysis recovered MLP 15-I-7–48 as sister group of the lower Maastrichtian Vegasaurus molyi within a new clade nominated as Weddellonectia: Kawanectes lafquenianum ((Vegasaurus molyi; MLP 15-I-7–48) (Morenosaurus stocki (Aristonectinae))). This indicates that the previously proposed faunal turnover between the early and late Maastrichtian Weddellian marine reptile fauna, did not severely affect the non-aristonectine elasmosaurids. Additionally, other taxa previously considered evidence of a faunal turnover are re-evaluated.

José P. O’Gorman. [[email protected]]. División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina. Rodolfo A. Coria. [[email protected]]. Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro—Subsecretaría de Cultura de Neuquén—Museo Carmen Funes, Av. CVórdoba 55 (8318), Plaza Huincul, Neuquén, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.

Key words:

• Weddellian Biogeographic Province
• Elasmosauridae
• Aristonectinae
• Antarctica

Acknowledgements

This research was supported by projects PICTO 2010-0093; PIP 0433, UNLP N 607, and PICT 2012-0748. The authors thank M. Cardenas, L. Chornogubsky, G. López, and M. Reguero for their assistance during fieldwork and K. Kamra for English editing of the manuscript and A. Roberts (University of Southampton) and P. Vincent (Muséum National d’Histoire Naturelle) for the comments that impoved this contribution. This contribution would not have been possible without logistical support from the Instituto Antártico Argentino and the Fuerza Aérea Argentina (Dotación 47° of Base Marambio). I. Cerda (Museo de Cinco Saltos), M. Reguero (MLP), D. Cabaza (MML), P. Scofield (UC), L. Chiappe and M. Walsh (Dinosaur Institute, LACM), and P. Holroyd and C. Mexia (UCPM, Berkeley) allowed access to specimens under their care.