Abstract

DEL MORAL SACHETTI, J. Fernando; ZENTENO CARDENAS, Ramiro  and  LAMEDA CAMACARO, Fátima I.. Biostatical analysis of the tensions acting in the jaw of the Andean bear (Tremarctos ornatus) during the bite. Acta Zool. Mex [online]. 2009, vol.25, n.3, pp.551-567. ISSN 2448-8445.

This study was intended to contribute to the biological and biostatical knowledge of the Andean bear, the fourth bear largest in the world and the largest carnivore living in the Neotropics. Tensions were high, asking the tooth during, their reactions and behavior cutting efforts and maximum flexor moments, along the jaw vain. This will be analyzed 3 complete skulls and a jaw from wild animals of Bolivia, using 9 skull measurements as descriptors. The maximum bite requests were considered in the canines (c) and second upper molars (m₂). It also determined the intensity of them, by calculating of the tensions reached higher in these sections, depending on the Fracture strength (σ_R = 0.50 kg/mm²). The final system, responds to two portions of a hiperestatical structure and its resolution is achieved through the Moment Distribution Method by Cross. It was found that the maximum bite force in the male is 246.90 kg being 1.34 times higher in the molars. The female, have reached a bite of 184.96 kg and a milling intensity of 285.75 kg. The increased intensity in over 80 kg in the molars on the canines is directly proportional to the great development of the temporalis-masseteric muscle, as the structural design of bone in the masseteric fossa and the width of face at molar. These biostatics characters reflect the design expertise craniodental of the species to withstand major stresses, product of crushing and grinding tough fibrous plants in general and training unique to the male predation. What it enables the Andean bear to have a varied diet and opportunistic in its ecological niche, adaptable to food resources that the environment offered.

Keywords : Andean bear; Tremarctos ornatus; biostatic; hiperestaticity; Cross method.

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