Primer registro de Borhyaenoidea (Mammalia, Metatheria, Sparassodonta) en la provincia de Tucumán (Formación India Muerta, Grupo Choromoro; Mioceno tardío)

Abstract

“First Record of Borhyaenoidea (Mammalia, Metatheria, Sparassodonta) of Tucumán Province (India Muerta Formation, Choromoro Group; Late Miocene)”. We describe the first Sparassodonta from Tucumán Province found in the India Muerta Formation (Choro- moro Group; Huayquerian South American Land Mammal Age). The material is represented by a fragment of a right mandible bearing the alveoli of the canine and premolars and m1-m4 partially preserved. The presence of wide and basined talonid, big first mentonian foramen, and similar length in the dental series suggest a close resemblance between the specimen of Tucumán and the genus Stylocynus from the Ituzaingó Formation (Paraná, Entre Ríos). In the context of the phylogeny of the borhyaenoids, a well-developed and basined talonid are con- sidered primitive traits defining the most basal taxa. The material from Tucuman and Stylocynus show this generalized pattern, although some differences ( e.g ., talonid deeply basined) indicate a derived morphology on the molars. From a functional point of view, the morphology of the lower molars of the specimen from Tucumán indicates an omnivorous diet that contrasts with that inferred for most of the Miocene borhyaenoids which exhibits clear adaptations for a car- nivorous diet.