Abstract

MAMANI, Claudio A.; LEARDI, Juan M.  and  DESOJO, Julia B.. New postcranial remains of Crocodylomorpha (Archosauria; Pseudosuchia) from the Los Colorados Formation (Late Triassic), La Rioja Province, Argentina. Rev. Mus. Argent. Cienc. Nat. [online]. 2022, vol.24, n.1, pp.47-76. ISSN 1853-0400.  http://dx.doi.org/10.22179/revmacn.24.743.

In the present contribution we study a fragmentary specimen of Crocodylomorpha recovered from outcrops of the Los Colorados Formation (Late Triassic) of the Ischigualasto-Villa Unión Basin. The material (PULR-V126) was deposited in the Museo de Ciencias Naturales of the Universidad Nacional de La Rioja, without any other data of origin or collector. The specimen consists of scarce postcranial remains, which include associated dorsal and caudal vertebrae, the proximal end of the humerus, and the proximal and distal ends of the femur, among other elements. The detailed study of the anatomy of the specimen was performed and a single autapomorphy was recognized: transverse processes of its middle/posterior dorsal vertebrae have a strong dorsolateral orientation. However, given the scarce remains of PULR-V126, we consider that this trait is not enough to support the creation of a new taxon based on this material. The specimen was included in a previously published morphological phylogenetic character matrix, in which both the sampling of taxa (2) and postcranial characters (1) were increased. Specimen PULR-V126 is recovered in several positions as a non-crocodyliform crocodylomorph in the different most parsimonious trees. This is caused by the lack of preservation informative characters in PULR-V126 that precluded the evaluation of its precise phylogenetic relationships within other crocodylomorphs.

Keywords : Taxonomy; Phylogeny; Mesozoic; Ischigualasto-Villa Unión Basin; South America.

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