New appendicular material ofSkorpiovenator bustingorryi (Theropoda, Abelisauridae) from the Huincul formation (cenomanian, upper Cretaceous), Patagonia, Argentina

BAIANO, M.A.; CERRONI, M.A.; CANALE, JUAN I.

Congreso; Reunion Anual de Comunicaciones de la Asociacion Paleotologica Argentina; 2019

The abelisaurid Skorpiovenator bustingorryi Canale et al., 2009, is known by an almost complete skeleton, recovered from thelowest section of the Huincul Formation (Cenomanian, Upper Cretaceous) near El Chocón town, Province of Neuquén. Althoughboth tibiae of the holotype were recovered, their proximal ends are incomplete, preventing the observation of someimportant characters of cnemial crest. Here we present a proximal end of a right tibia (MMCh-PV 255), which by its geographicaland stratigraphical provenance, and equivalent morphology with the holotype, can be confidently assigned toSkorpiovenator. As in other abelisauroids, the cnemial crest is well developed andanterodorsally projected. Moreover, thiscrest shows a hatchet-shaped morphology, with a subrectangular outline in lateral view, also observed in some abelisauridsas Pycnonemosaurus Kellner and Campos, 2002, Ekrixinatosaurus Calvo et al., 2004 and Aucasaurus Coria et al., 2002. Over themediodistal sector of the cnemial crest there is a small lateral accessory process, also observed in Aucasaurus. In proximalview the lateral condyle is much wider than the medial one, as in Aucasaurus and Xenotarsosaurus Martínez et al., 1986, andboth condyles shows a subquadrangular outline, with flat posterior margins; a trait not observed in other abelisaurids,which could represent an autapomorphy of Skorpiovenator. The excellent preservation of the bone surface allows establishingclear sectors of muscular insertion; including mm. iliotibialis, femorotibialis, ambiens and gastrocnemius. Although fragmentary,this new material adds novel information about the anatomy of Skorpiovenator, allowing the recognition of a possibleautapomorphy and some characters of potential phylogenetic significance.