IBS   24490
INSTITUTO DE BIOLOGIA SUBTROPICAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Limb elements of and extinct sigmodontine from the Pleistocene of Argentina. Possible locomotor types in Tafimys powelli.
Autor/es:
CARRIZO, L. V; ORTIZ, P. E
Lugar:
Mendoza
Reunión:
Congreso; 4th international palaeontological congress,; 2014
Resumen:
The fossil record for rodents of the predominantly South American Subfamily Sigmodontinae (Mammalia: Rodentia: Cricetidae) is based almost exclusively on cranial and dental elements. Very limited data are known for the rest of the skeleton in fossil forms. Here we present the first study of postcranial elements for an extinct sigmodontine, Tafimys powelli, known only for the Pleistocene of Northwestern Argentina. The studied material comes from the Tafí del Valle Formation, La Angostura, Tucumán province, Argentina, and was recovered from a very rich rodent assemblage constituted by more than 300 individuals belonging to 15 species. In this assemblage T. powelli was the dominant species, reaching more than 60% of all the recovered specimens according to the number of mandibles and maxillae. Here we present a description of previously unknown limb bones (ulna, humerus and femur) of this sigmodontine, with the purpose to infer the probable locomotor behaviour of this extinct mouse. Limb bones of species pertaining to all the extant rodent genera recorded in the Pleistocene site (Abrothrix, Akodon, Necromys, Oxymycterus, Oligoryzomys, Calomys, Phyllotis, Reithrodon, Neotomys, Andinomys, Cavia, Galea, and Ctenomys) were used for comparison. Postcranial bones of Tafimys were identified because they present a similar proportion to that found in the cranial remains and because this dominant morphology was quite different from any of the rodent species represented in the fossiliferous deposit. We measured the lengths and midshaft diameters of the limb bones of fossil and living rats to compute 20 functional indices indicative of locomotor adaptations. The humerus, ulna and femur of Tafimys show the main osteological features related to terrestrial locomotive type (e.g., short medial humeral epicondyle; elongated olecranon process of the ulna; higher greater trochanter; lesser trochanter posteriorly placed). This suggests that Tafimys powelli possibly presented abilities consistent with a model of a generalized sigmodontine that move mainly on the ground but could readily dig. Our results also find that limb bones of Tafimys present a general morphological pattern similar to genera belonging to Abrotrichini and Akodontini tribes (Abrothrix, Akodon, and Necromys).