Kinematics and Comparative Anatomy of Some Limb Bones of the African Elephant (Loxodonta africana) and Large Domestic Animals
نویسنده
چکیده
Elephants are the largest extant terrestrial animals and the archetype of ‘graviportal’ animals, with large body size and a pattern of pentadactyl limbs. The fundamental structures are homologous in all tetrapods but in the course of evolution these structures have been modified in the elephant. Osteometric parameters show that the relationship of the length of the femur to the circumference is 2.5, 2.75 and 2.8 in elephant, horse and cattle respectively. Similarly humerus length to circumference is 2.3 in the three species showing isometric scaling. There is a positive allometric scaling between bone weight and bone length; the ratio of femur length to weight is 205g/cm, 72g/cm and 64g/cm in elephants, horses and cattle. The ratio of weight of the humerus to length or weights of the humerus plus femur to their combined length is a good estimate of the body weight in kg= ( ). We have observed three gaits in the elephant: slow, fast walk, and trot. Either one or a maximum of two controlateral legs are lifted from ground, but never two ipislateral limbs. The propulsive force originates from the retractor muscles of the hind legs, elephants moving by extension of the forelegs rather than flexion. The head’s conical structure makes it aerodynamically efficient, serving as nose cone. The joint Articulatio atlanto occipitalis is less movable than the horse or cattle. The main mechanism by which an elephant overcomes the effect of heavy weight is by having high density bones. The articular surfaces of the bones are less developed in elephant compared to horse or cattle, resulting in poor angular movements with less ground shock waves. The pes is like a cushion filled with a fat layer that serves as a shock absorber. The skull is spongy and the arrangement
منابع مشابه
Dwarfing a Giant: Allometry and Ontogeny of Elephant Limb Bones
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تاریخ انتشار 2012