Craniometria e anatomia óssea do crânio de Tapirus terrestris (Perissodactyla – Tapiridae)

Abstract

The aim of this study was to describe the skull bones of Tapirus terrestris (Linnaeus - 1758) and this study was to obtain measurements in adult skulls of T. terrestris, establishing a standardization of craniometric values for this species. Six adult tapir skulls were used. The specimens are part of the didactic collection of the Laboratory of Teaching and Research in Wild Animals of UFU. The skulls were treated with usual maceration techniques. It was defined the localization of 20 craniometric points used in horses according to Von Den Driesch (1976) and 48 linear measures were carried out from the points. The skull is composed by the following bones: Occipital, Sphenoid (Basisphenoid, Presphenoid), Temporal, Frontal, Parietal, Interparietal, Nasal, Lacrimal, Zygomatic, Maxilla, Incisive, Palatine, Vomer, Etmoid, Pterygoid and Mandible. The skull of T. terrestris has several accidents and bony characteristics similar to equines; however, differences are found when compared to the other Perissodactyla, such as non-existent zygomatic process of frontal, changes in palatine suture, lateral aspect of the mandible, condylar process and the labial aspect of the incisive bone, as well as the absence of a clear division between presphenoid and basisphenoid, fused interparietal bones and modified nasal bones, and others. Therefore, different species of animals present specific and distinct morphological characteristics of the skull, adapted for each type of environment and food. Afterwards, six craniometric indices were verified. It can be concluded that in most points and measurements presented low variations. It was observed that there is a positive correlation between the variables Skull and Mandible and that, with the model proposed to this study for each unit of maxilla, the expected variation is 0.4179. The six craniometric indexes presented the following values from the mean ± standard deviation: cephalic 22.56 ± 0.56 mm, facial skeleton 1.92 ± 0.09 mm, neurocranium 55.07 ± 2.48 mm, facial 43.76 ± 2, 02 mm, basal 17.11 ± 1.51 mm, and of the foramen magnum 67.18 ± 12.43 mm. Variations around the averages are low. There is the evidence that the variable of the Neurokranium index is not a good measure that allows explaining a variable of cephalic index.