Southernmost lepidosaur (Reptilia) assemblage from the Late Cretaceous of Patagonia

ABSTRACT

The aim of the present contribution is to describe new materials of lepidosaur reptiles coming from the late Cretaceous (Maastrichtian) Chorrillo Formation, at Santa Cruz province, Argentina. The lepidosaur assemblage is composed by four different snakes (belonging to basal snakes, madtsoiids, and ‘anilioids’) and a tuatara sphenodont. The latter is a new genus and species represented by an incomplete maxilla that shows strong ties to extant Sphenodon. The snakes are represented by isolated vertebrae that indicate they belong to basal forms. Both are very apomorphic and in all probability are the representatives of poorly known lineages. In contrast with recent claims, the fact that most members of this lepidosaur assemblage are highly apomorphic may be indicative of some biogeographical isolation from other Cretaceous lepidosaur associations reported from northern Patagonia.

KEYWORDS:

• Lepidosauria
• sphenodontidae
• “anilioidea”
• madtsoiidae
• basal snakes

Acknowledgments

Thanks to the late Coleman Burke (New York) for his encouragement and financial assistance to carry on first field explorations to La Anita farm. Dr. Yoshihiro Hayashi, former Director General, National Museum of Nature and Science, Japan, for his support for the project by funding a major part of the expedition from the internal grant from the museum. Facundo Echeverría and his wife Daphne Fraser (La Anita farm) offered their help during the field trip. Oscar Canto and Carla Almazán (Secretaría de Cultura) for supporting our projects and explorations in Santa Cruz. We thank F. Brissón Eglí, N. Chimento, G. Muñoz, M. Cerroni, S. Miner, G. Álvarez-Herrera and members of the LACEV team for their help during the excavation and technical preparation of the specimen. Special thanks to Ana P. Moreno for technical preparation of specimens and for the finding of the snake genera and species 1 and 2. Special thanks to anonymous reviewers and the editor Gareth Dyke, for their comments on the original MS.

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