Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina

Abstract

O’Gorman, J.P., Salgado, L., Varela, J., & Parras, A., 2013. Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina. Alcheringa 37, 257–265. ISSN 0311-5518.

Elasmosaur postcranial remains from the La Colonia Formation (Campanian–Maastrichtian), Chubut Province, Patagonia, Argentina, are described. The new material has small dimensions and caudal vertebrae with parapophyses strongly projected laterally—characters shared with some Elasmosauridae indet. from the coeval Allen Formation, Río Negro Province, Argentina. These features reinforce the similarities between the plesiosaur faunas to the north and south of the Somún Curá Plateau. The small size of these elasmosaurs may be palaeoecologically related to the marginal marine depositional environment of the sedimentary host rocks.

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 and [CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas)]; Leonardo Salgado [[email protected]], Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Isidro Lobo y Belgrano, 8332 General Roca, Argentina and [CONICET]; Julio Varela [[email protected]], and Ana Parras [[email protected]], INCITAP (CONICET-UNLPam), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina. Received 27.7.2012; revised 19.10.2012; accepted 27.10.2012.

本文描述了阿根廷Patagonia的Chubut省La Colonia组(Campanian-Maastrichtian)的薄片龙无颅化石。新材料个体小, 尾椎骨上有向两侧的突伸。这些特征与出现在阿根廷Río Negro 省Allen组中的一些同时的薄片龙不定种相同, 并进一步证明了Somún Curá高原南部和北部的蛇颈龙动物群之间的相似性。这些薄片龙个体小, 可能在古生态上与主体沉积岩石的边缘海沉积环境有关。

Key words:

• Allen Formation
• Upper Cretaceous
• Elasmosauridae
• Patagonia
• palaeoecology

Acknowledgements

This research was supported by projects PIP 0426, UNLP N607 and PICT 2008-0261 (ANPCyT). Ruigómez (Curator of the MPEF collection) for the loan of the material, J. Sterli, P. Puerta and B. Rosso for collaboration in the field and P. Gallina for providing literature.