ANATOMY AND SYSTEMATIC OF PROSQUALODON AUSTRALIS (CETACEA, ODONTOCETI) FROM THE EARLY MIOCENE OF PATAGONIA

GAETÁN, CARLOS MAXIMILIANO; BUONO, MÓNICA R.; GAETANO, LEANDRO

Jornada; XXXII JORNADAS ARGENTINAS DE PALEONTOLOGÍA DE VERTEBRADOS VII JORNADAS TÉCNICAS DE PALEONTOLOGÍA DE VERTEBRADOS; 2018

The extinct odontocete Prosqualodon australis Lydekker, 1894 (Early Miocene, Gaiman Formation, Chubut Province, Argentina) is for the first time described in-depth based on the holotype (MLP 5-8, a partial skull) and a referred specimen (MLP 5-9, an almost complete skull; Cabrera, 1926). Besides, the first phylogenetic analysis including this species as an operational taxonomic unit itself is presented, considering a comprehensive morphological matrix of odontocetes. The peculiar morphology of the anterior projection of the antorbital process along with plesiomorphic dental features (such as well-marked heterodont, large lateromedially compressed teeth with long crowns, reticulated enamel, and birradiculated teeth in the maxillae) are proposed to diagnose the species. Also, the body length of P. australis is inferred to vary at least between 2 and 3 m between the juvenile and the adult stages. Comparative anatomical studies show ontogenetic and intraspecific differences between the specimens analyzed. The phylogenetic analyses show P. australis as a stem-Odontoceti and Prosqualodon as a paraphyletic genus. The relative basal position of P. australis in the optimal trees recovered may respond to plesiomorphic skull characteristics. Also due to the lack of preserved earbones in P. australis, the future description of tympano-periotic bones might lead to new phylogenetic results.