A peculiar ossification of the skull of Neosclerocalyptus Paula Couto, 1957 (Mammalia: Cingulata)

FERNICOLA, J. C.; TOLEDO, N.; VIZCAÍNO, S. F.; BARGO, M. S.

Paris, Francia

Congreso; 8th Interntional congress of Vertebrate Morphology; 2007

International Society of Vertebrate Morphologists

In glyptodonts many sutures of the skull are obliterated during ontogenetic development, hindering the recognition of the different bony elements that compose it. A detailed revision of a number of skulls assigned to different glyptodontids brought to attention several skulls with precise bony limits that permit the identification of previously undescribed bony elements. In this communication we describe a peculiar bony element observed only in several adult individuals of the Pleistocene genus Neosclerocalyptus housed at Museo Argentino de Ciencias Naturales of Buenos Aires and Museo de La Plata (Argentina). The dorsal surface of the skull presents clear sutures for the parietal, frontal and nasal bones. The anterior margin of the latter partially overlaps a fourth bony element, the exposed surface of which represents, in dorsal view, nearly one quarter of total skull length. Laterally, this element is overlapped by the premaxillae. We interpret this structure as comprising the ossified nasal cartilages, separated internally by a triangular and ossified septum nasi. The following anatomical structures are identified: dorsally the tectum nasi extends anteriorly with the cartilago cupularis and laterally with the paries nasi. A longitudinal depression between the latter and the tectum nasi may represent an obliterated fenestra superioris nasi. The paries nasi projects medially into a fold that expands within the extensive turbinal (marginoturbinal?) and medioventrally as a plate that possibly represents the processus superioris alaris.