INVESTIGADORES
BOND mariano
congresos y reuniones científicas
Título:
AN UNUSUAL AND AMAZING NOTOUNGULATE FROM THE MIOCENE OF CORDILLERA FRONTAL OF SAN JUAN PROVINCE, ARGENTINA
Autor/es:
LÓPEZ, G.M., BOND, M. AND J.N. GELFO
Lugar:
San Juan
Reunión:
Congreso; IV Congreso de Paleontología de Vertebrados; 2011
Institución organizadora:
Universidad Nacional de San Juan
Resumen:
AN UNUSUAL AND AMAZING NOTOUNGULATE FROM THE MIOCENE OF CORDILLERA FRONTAL OF SAN JUAN PROVINCE,ARGENTINAG.M. LÓPEZ1-2, M. BOND1-2-3 and J.N. GELFO1-2-31División Paleontología de Vertebrados, Museo de La Plata. Paseo del Bosque s/n B1900FWA, La Plata, Buenos Aires, Argentina2Facultad de Ciencias Naturales y Museo, UNLP3Consejo Nacional de Investigaciones Técnicas y Científicas (CONICET)The Manantiales Basin is located in Los Patos valley, in the Cordillera Frontal of San Juan province. The thick Neogene deposits exposedalong the Los Patos river, between Las Hornillas and Horcajo, was defined by Mirré (1966) as the Chinches Formation. This sedimentarysuccession, more than 2000 m thick, has been divided into seven members, and their ages have been inferred by radiometric and magnetostratigraphicstudies. Abundant fossil mammals (marsupials, Xenarthra, four families of notoungulates, litopterns and six groups of rodents)were reported by López et al. (in press) from two different levels of the lowest third of the Chinches Formation. The faunal assemblages ofboth levels were referred to the Santacrucian SALMA (late early Miocene) and are relevant because they have an intermediate latitudinallocation between Miocene faunas from Patagonia and the Altiplano (Chile and Bolivia). Here we describe three specimens of associatedcrania (approximately 45 mm length) and mandibles, housed in the Museo de Ciencias Naturales of San Juan province, from the lowest fossilbearinghorizon. The remains belong to adult specimens (erupted M3/3) of unusual notoungulate (?typotherian) with a high and very shortrostrum that curiously more resembles that of groeberiida marsupials than rodent-like notoungulates. The specimens resemble interatheriineinteratheriids in having: hypsodont lower and upper cheek teeth with cement; bilobed M1-2 with a well defined lingual sulcus and slightlyundulated ectoloph; lower molars with subcircular trigonid and talonid of similar size. However, this taxon has unusual features such as: (1)incomplete dentition (I1/2 C0/0 P3/2 M3/3) but without diastema; (2) hypsodont and hypertrophied I1; (3) i1 distinctly smaller than i2and positioned anterior and closely appressed to i2; (4) a peculiar flat shelf on the ventral side of the symphysis; (5) two foramina in the innerside of the symphysis (?subalveolar fossa); and (6) well developed incisive and palatine foramina. These unique characters may argue for anew lineage of notoungulates that represents a new adaptive type for South American native ungulates.López, G.M., Vucetich, M.G., Carlini, A.A., Bond, M., Pérez, M.E., Ciancio, M.R., Pérez, D.J., Arnal, M. and Olivares, A.I. (in press). New Miocene mammalassemblages from Neogene Manantiales basin, Cordillera Frontal, San Juan, Argentina. In: J.A. Salfity and R.A. Marquillas (Eds.), Cenozoic Geologyof the Central Andes of Argentina. Salta, Instituto del Cenozoico, Universidad Nacional de Salta.Mirré, J.C. 1966. Geología del Valle del Río de Los Patos (entre Barreal y Las Hornillas). Revista de la Asociación Geológica Argentina 21: 211-232.