A new specimen of Uruguaysuchus aznarezi (Crocodyliformes: Notosuchia) from the Cretaceous of Uruguay and its phylogenetic relationships

SOTO, M.; POL, D.; PEREA, D.

ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

Wiley-Blackwell

Lugar: London; Año: 2011 vol. 163 p. 173 - 198

0024-4082

Uruguaysuchus is a small mesoeucrocodylian known from several partial skeletons andskulls from the Guichón Formation (middle Cretaceous, Uruguay). Several authors havepointed out derived similarities of this taxon with different basal notosuchian genera,highlighting its importance for mesoeucrocodylian phylogeny and biogeography.However, the holotype is only partially prepared and has not been available for studyfor many years. Thus, phylogenetic studies have included this form based on theoriginal description, thereby resulting in a large amount of missing data in the characterscorings of this taxon. Here, we describe a new specimen from the type localityconsisting of a partial skull, lower jaw and cervical vertebrae which can be referred toU. aznarezi. The new specimen allows for the recognition and scoring of severalcharacters previously unknown for this taxon, thus providing a more extensivediagnosis, as well as new information for understanding its phylogenetic relationships.These characters are congruent with the morphology present in basal notosuchians. The relationships of Uruguaysuchus are tested through a cladistic analysis using a recentlypublished data set including the new information. The phylogenetic results differ fromprevious analyses, recovering this taxon as the sister group of the Araripesuchus clade.U. terrai is considered a juvenile individual of U. aznarezi.