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Basal sauropodomorphs from the Ischigualasto Formation

2012; Taylor & Francis; Volume: 32; Issue: sup1 Linguagem: Inglês

10.1080/02724634.2013.819361

1937-2809

Ricardo N. Martínez, Cecilia Apaldetti, Diego Abelín,

Geological formations and processes

ABSTRACT Basal sauropodomorphs from the Ischigualasto Formation include Eoraptor lunensis, Panphagia protos, and Chromogisaurus novasi. Few comparisons have been made between these taxa, because Eoraptor was only recently reassessed as a basal sauropodomorph and because Panphagia and Chromogisaurus were described nearly simultaneously. We describe in detail the fully prepared bones of the holotype of Chromogisaurus novasi, examine the evidence for its taxonomic distinction, and analyze the phylogenetic relationships among basal sauropodomorphs. Our results support Chromogisaurus novasi as a valid genus and species and provide weak phylogenetic evidence favoring a series of stem taxa at the base of Sauropodomorpha. The analysis positions Panphagia as the basal-most sauropodomorph, followed by Eoraptor, Pampadromaeus, and a clade that includes Chromogisaurus and Saturnalia. RESUMEN—Los sauropodomorfos basales de la Formación Ischigualasto incluyen Eoraptor lunensis, Panphagia protos y Chromogisaurus novasi. Pocas comparaciones se han hecho entre estos taxones, porque Eoraptor fue reevaluado recientemente como sauropodomorfo basal y porque Panphagia y Chromogisaurus se describieron de forma casi simultánea. Describimos en detalle los huesos totalmente preparados del holotipo de Chromogisaurus novasi, examinamos la evidencia de su distinción taxonómica, y analizamos la relación filogenética entre sauropodomorfos basales. Nuestros resultados apoyan a Chromogisaurus novasi como un género y especie válido y proporcionan débil soporte filogenético favoreciendo un arreglo parafilético en la base de Sauropodomorpha. El análisis posiciona a Panphagia como el sauropodomorfo más basal, seguido de Eoraptor, Pampadromaeus y un clado que incluye a Chromogisaurus y Saturnalia. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP ACKNOWLEDGMENTS We thank C. Abraczinskas for assistance in preparing the final figures. We also thank the Earthwatch Institute for support of field work and for the many Earthwatch field volunteers and the Instituto y Museo de Ciencias Naturales of the Universidad Nacional de San Juan and CICITCA for their support of this research. We thank P. Mannion, A. Yates, and M. Langer for their critical reviews, which improved the quality of the manuscript. Handling editor: Jeffrey Wilson.