Kinematics of some elephant limb bones Melaku Tefera Kinematics and Comparative Anatomy of Some 85 Limb Bones of the African Elephant (Loxodonta africana) and Large Domestic Animals 80 75 Melaku Tefera College of Veterinary Medicine, Haramaya University. 70 P.O. Box 144 Haramaya Campus. Ethiopia. 251-0914722459, [email protected] With 3 plates &2 figures Received May, accepted for publication December, 2011 TG 65 60 Abstract weight in kg= ( ). We have observed three gaits in the ele- 55 Elephants are the largest extant ter- phant: slow, fast walk, and trot. Ei- ther one or a maximum of two con- 50 restrial animals and the archetype of ‘graviportal’ animals, with large body trolateral legs are lifted from ground, 45 size and a pattern of pentadactyl but never two ipislateral limbs. The limbs. The fundamental structures propulsive force originates from the 40 are homologous in all tetrapods but retractor muscles of the hind legs, 12 15 18 21 24 27 30 33 36 in the course of evolution these elephants moving by extension of LV the forelegs rather than flexion. The structures have been modified in the Fig (2): Linear fit for live weight (LW) and thoracic girth (TG) and RMA analysis. (95 % elephant. Osteometric parameters head’s conical structure makes it confidence) show that the relationship of the aerodynamically efficient, serving as length of the femur to the circumfer- nose cone. The joint Articulatio at- LV (kg) = (0.659 x TG) (cm) – 17.467 ence is 2.5, 2.75 and 2.8 in ele- lanto occipitalis is less movable than RMA Regression phant, horse and cattle respectively. the horse or cattle. The main mech- Slope a: 0.65974 Similarly humerus length to circum- anism by which an elephant over- Intercept b: -17.467 ference is 2.3 in the three species comes the effect of heavy weight is Std. err. a: 0.056768 Std. err. b: 11.189 showing isometric scaling. There is by having high density bones. The Chi squared: 0 a positive allometric scaling be- articular surfaces of the bones are r: 0.84335 2 tween bone weight and bone length; less developed in elephant com- R : 0.71125 pared to horse or cattle, resulting in t statistic: 9.8012 the ratio of femur length to weight is p(uncorrel): 4.505E-12 205g/cm, 72g/cm and 64g/cm in el- poor angular movements with less Permutat. p: 0.0001 ephants, horses and cattle. The ground shock waves. The pes is like p(a=1): 5.282E-07 ratio of weight of the humerus to a cushion filled with a fat layer that 95% bootstrapped confidence intervals: serves as a shock absorber. The a: [0.5001; 0.8068] length or weights of the humerus b: [-25.38; -8.735] plus femur to their combined length skull is spongy and the arrangement is a good estimate of the body J. Vet. Anat. 15 Vol 5 No 2, (2012) 15 - 31 Kinematics of some elephant limb bones Melaku Tefera of trabeculae makes the skull lighter (Loxodonta africana cyclotis) Severe scaling constraint on func- contact time (Alexander, et al., in weight. (Rohland, et al., 2010), all other tional capacity may result as organ- 1979). Our understanding of ele- species and genera of elephantidae isms evolve to large size. It has long phant locomotion is impaired by a Key words like Loxodonta adaurora (the pre- been recognized that body size is a lack of data. sumed ancestor of the modern Afri- critical factor influencing mechanical Hence the objective of this research biomechanics, bone allometry, can elephants) are extinct (Eggert, support of animals. Specifically, the is to study the anatomy of the long comparative anatomy, elephant, et al., 2002). ability of muscle to generate force or bones of both limbs of the elephant gait, osteology, skeleton, aerody- Elephant anatomy is poorly under- bones to resist force depends on and compare its morphology with namics. stood (Hutchinson, et al., 2006) and tissue cross-sectional area which some domestic animals, to see if access to specimens is severely decreases in proportion to an ani- there is an isometric or allometric Introduction difficult. The pattern of limb called mal’s weight with increased size. relationship between the osteomet- pentadactyl is an example of ho- The scaling of bone and muscle ge- ric parameters, describe the skull mologous structure found in all ometry in mammals suggests that bone and investigate the biome- The Order Proboscidea includes the classes of tetrapods. Suggesting force on the skeleton increases with chanics of the elephant gait. animals with elongated trunks that that they have originated from a increasing body size. McMahon, function both as nose and as a pre- common ancestor but in the course (1973) has proposed a scaling hensile organ to grasp and manipu- Materials and Methods of evolution these fundamental model of elastic similarity which ar- late objects in the environment. structures have changed. The paw gues that the linear dimensions of Modern elephants are the heaviest Osteology of the dog, the hoof of the horse, the animals do not increase in the same land animals, no other terrestrial The elephant (Loxodota africana manus and pes of the elephant and proportion. Instead bones increase animal weighs half as much africana) bones were property of foot of the human all share some in proportion to their diameter so (McMahon, 1975). There are two Haramaya University, Ethiopia. Five common features of structure, or- that animals become distorted in genera of the family Elephantidae: bones were acquired, two femora, a ganization and function. Each of shape and relatively more stout as Elephas and Loxodonta. The Asian humerus and two halves of the face these organisms’ foot structures they increase in size. Yet mammali- elephant (Elephas maximus) is also bone. The elephant was in the uni- function as the load transmission an limb bones scale close to isome- known as the Indian elephant, and versity zoo and died in the year platform which is essential to bal- try in proportion (Biewner, 1983). is found in Asia. The elephants of 1960. The condition of the bones ance, standing and locomotion Others (Russell, 1985) do not sup- the genus Loxodonta, known collec- was fair with slight erosions of the strategies (such as walking, trotting, port this hypothesis instead arguing tively as African elephants, are cur- periosteum, because the bones galloping and running). Elephants that large animals must compensate rently found in 37 countries in Africa were stored in outdoors in shed. as the largest extant terrestrial ani- for geometric scaling of their bones (Blanc, 2008; Elephant encyclope- The femur and humerus of cattle mals and as the archetype of ‘gravi- by reducing the forces acting on the dia). African elephants have tradi- and horse were property of Ha- portal’ animals, having large body bones of their skeleton. The most tionally been classified as a single ramaya University College of Veter- size with columnar, robust limbs effective way of achieving this re- species. However genetic study has inary Medicine, Anatomy Laborato- (Coombs, 1978); provide insight into duction is to reduce the bending shown that to comprise three dis- ry; they were two years old since the biomechanical and physiological force. Another mechanism is to re- tinct subspecies, namely the savan- slaughtering of the animals. The constraints that extremely large duce ground force exerted on the na elephant (Loxodonta africana bones were weighed using a digital body size imposes. limb during the support phase of africana and Loxodonta africana. balance. The length of bones was locomotion by reducing the ground knochenhaueri), the forest elephant measured using a tape measure J. Vet. Anat. 16 Vol 5 No 2, (2012) 15 - 31 Kinematics of some elephant limb bones Melaku Tefera of trabeculae makes the skull lighter (Loxodonta africana cyclotis) Severe scaling constraint on func- contact time (Alexander, et al., in weight. (Rohland, et al., 2010), all other tional capacity may result as organ- 1979). Our understanding of ele- species and genera of elephantidae isms evolve to large size. It has long phant locomotion is impaired by a Key words like Loxodonta adaurora (the pre- been recognized that body size is a lack of data. sumed ancestor of the modern Afri- critical factor influencing mechanical Hence the objective of this research biomechanics, bone allometry, can elephants) are extinct (Eggert, support of animals. Specifically, the is to study the anatomy of the long comparative anatomy, elephant, et al., 2002). ability of muscle to generate force or bones of both limbs of the elephant gait, osteology, skeleton, aerody- Elephant anatomy is poorly under- bones to resist force depends on and compare its morphology with namics. stood (Hutchinson, et al., 2006) and tissue cross-sectional area which some domestic animals, to see if access to specimens is severely decreases in proportion to an ani- there is an isometric or allometric Introduction difficult. The pattern of limb called mal’s weight with increased size. relationship between the osteomet- pentadactyl is an example of ho- The scaling of bone and muscle ge- ric parameters, describe the skull mologous structure found in all ometry in mammals suggests that bone and investigate the biome- The Order Proboscidea includes the classes of tetrapods. Suggesting force on the skeleton increases with chanics of the elephant gait. animals with elongated trunks that that they have originated from a increasing body size. McMahon, function both as nose and as a pre- common ancestor but in the course (1973) has proposed a scaling hensile organ to grasp and manipu- Materials and Methods of evolution these fundamental model of elastic similarity which ar- late objects in the environment. structures have changed.