Diagnosis and new description of Propanochthus bullifer (Burmeister) (Xenarthra, Glyptodontidae). Biostratigraphic and chronological considerations of their origin
División de Paleontología de Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata. Paseo del Bosque s/n, 1900 La Plata. Argentina. CONICET. Cátedra de Zoología Vertebrados. email@example.com
Xenarthra is a diverse group of mammals characteristic of the Neotropical Region. They occur in South America and they are primarily classified into two large groups: Pilosa and Cingulata. The Glyptodontidae are the larger-sized Cingulata group and are recorded from the middle Eocene until the early Holocene; it is noticeable the presence of a dorsal carapace with rigid sutures, in contrast with the other Cingulata (dasypodid and pampatheres). Burmeister recognized Panochthus bullifer, on the basis of fossils from Neogene sediments of the sierras in Córdoba Province. In 1925 Castellanos founded, for this species, the genus Propanochthus, on the ground that the anatomical features of Panochthus bullifer are sufficiently different from the other species of Panochthus. Type material of this species is derived comes from the “Brocherian” of Castellanos. This species was traditionally placed in the “Hoplophorinae” subfamily and “Panochthini” tribe; recent phylogenetic analysis showed that neither of them is a natural group. This contribution provides the first formal diagnosis of Propanochthus bullifer. It also describes the material using a more up-todate and appropriate terminology, comparing it with the related species. The holotype corresponds to a fragment of the postero-dorsal region of the dorsal carapace and the complete caudal tube. The ornamentation of the osteoderms of the carapace has a large central figure surrounded by up to five rows of peripheral small figures. The central figure is flat in the anterior area, convex in the posterior area, and fairly blistered on the margin. In the osteoderms of the posterior margin, the central figure lies caudally, preceded by up to seven rows of small figures. The caudal tube is slightly smaller than in Panochthus; it is depressed and its distal end is notoriously blunt. In dorsal view, the ornamentation consists of flat central figures surrounded by a row (occasionally two rows) of peripheral figures. In lateral view, it has four large sub-elliptical rough figures surrounded by small figures and separated from each other by two opposing smaller subelliptical rough figures. Furthermore, the stratigraphic and geographic distribution of the species is defined, Brochero Formation (Montehermosan-Chapadmalalan [early Pliocenelate Pliocene]) of the Sierras de Córdoba, and the antiquity is discussed.
Keywords: Propanochthus bullifer, Brochero Formation, Neogene, Glyptodontidae, Argentine.
How to cite: Zamorano, M. 2013. Diagnosis y nueva descripción de Propanochthus bullifer (Bermaister) (Xenarthra, Glyptodontidae). Condideraciones bioestratigráficas y cronológicas de su procedencia. [Diagnosis and new description of Propanochthus bullifer (Burmeister) (Xenarthra, Glyptodontidae). Biostratigraphic and chronological considerations of their origin]. Spanish Journal of Palaeontology, 28 (2), 283-292.
Received 29 March 2013, Accepted 26 July 2013, Published 31 December 2013