Oligocene Glyptodontidae (Mammalia, Cingulata) from the Fray Bentos Formation of Uruguay

BOSTELMANN, ENRIQUE; RINDERKNECHT, ANDRÉS; CIANCIO, MARTÍN R.; PEREA, DANIEL

Montevideo, Uruguay

Congreso; I Congreso Uruguayo de Zoología y X Jornadas de Zoología del Uruguay; 2010

Sociedad Zoológica del Uruguay

Excluding the enigmatic Glyptatelinae, Paleogene glyptodontids are extremely rare in the fossil record. Indeed, the only unquestionable published remains belong to isolated osteoderms assigned to an unidentified Propalaehoplophorinae from the late Oligocene El Pajarito locality of Chubut Province, Argentina. Nevertheless, the first mention of Oligocene glyptodontids was made by A. Castellanos based on two isolated osteoderms collected in the Barranca de Los Loros, at the Colonia Department, southwestern Uruguay. The paleontology collection of the Museo Municipal “Prof. Lucas Roselli” (MLR) houses remains of an unpublished “non glyptateline” glyptodontid labeled as [“Bertawileria” sp.], here described in detail. MRL 702 includes ten almost complete osteoderms exhumed from the Fray Bentos Formation mudstones, in the “Barrancas de la Zona Franca del Puerto de Nueva Palmira”, a now disappeared locality supplanted by the facilities of the international harbor. The remains represent different regions of the carapace; four partial osteoderms from the dorso-lateral area; three lateral rectangular ones; two from the lateral border; and one anterior semi-mobile piece. All of them exhibit a punctuated, flat and smooth external surface, with rugose extensions on the contact zone. Ornamentation consists in the typical “rossetta”-pattern with an almost circular big central figure surrounded by numerous small prismatic peripheral figures, all delimited by shallow narrow sulcus with small foramina in their intersections. In accordance to this morphology we tentatively assign the remains to Propalaehoplophorinae indet. MLR 701 consists in three postcranial remains associated to 702: 1) the proximal portion of a right tibia with the articular surfaces for the femur; 2) a possible carpal bone, and 3) one fragmented articular bone of uncertain position. Our investigations shows that the past diversity of Oligocene Cingulata in Uruguay, while scant, is quite relevant to improve a better knowledge on the early diversity of South American fossil cingulates.