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1 January 2013 Emended Diagnosis and Phylogenetic Relationships of the Upper Cretaceous Fossil Snake Najash rionegrina Apesteguía and Zaher, 2006
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Abstract

The fossil snake Najash rionegrina, from the Cenomanian—Turonian (Upper Cretaceous) of Argentina, is reinterpreted after examination of the type and referred material. The current diagnosis is emended in the light of important considerations that cast doubt on the attribution of type and referred specimens (a braincase, a quadrate, and two dentary/lower jaw fragments) used to systematize this taxon. Alternative interpretations of the anatomy of the sacrum and hind limbs are proposed. Following the reevaluation of the anatomy of the type specimen and the removal from this taxon of the above-mentioned referred material, the phylogenetic position of N. rionegrina was tested in a series of maximum parsimony analyses that included all groups of extant snakes, all best-known fossil snakes (i.e., Pachyrhachis, Haasiophis, Eupodophis, Madtsoiidae, and Dinilysia), and alternative outgroups. Regardless of the outgroup used to polarize the character-state transformations, our phylogenetic analyses found no support for the hypothesis that Najash rionegrina occupies a position as the most basal snake. Depending on the outgroup, Najash is placed (1) in a position basal to all living snakes, but more derived than other fossil forms (most notably Pachyrhachis, Eupodophis, and Haasiophis); or (2) as the most basal representative of a clade of fossil snakes that is the sister group of living snakes; or (3) as the most basal representative of a clade of fossil snakes that is located between the Scolecophidia and the Alethinophidia.

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

© 2013 by the Society of Vertebrate Paleontology
Alessandro Palci, Michael W. Caldwell, and Adriana M. Albino "Emended Diagnosis and Phylogenetic Relationships of the Upper Cretaceous Fossil Snake Najash rionegrina Apesteguía and Zaher, 2006," Journal of Vertebrate Paleontology 33(1), 131-140, (1 January 2013). https://doi.org/10.1080/02724634.2012.713415
Received: 2 February 2012; Accepted: 1 July 2012; Published: 1 January 2013
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