Spotted hyena

The spotted hyena has a strong and well developed neck and forequarters, but relatively underdeveloped hindquarters. The rump is rounded rather than angular, which prevents attackers coming from behind from getting a firm grip on it. The head is wide and flat with a blunt muzzle and broad rhinarium. In contrast to the striped hyena, the ears of the spotted hyena are rounded rather than pointed. Each foot has four digits, which are webbed and armed with short, stout and blunt claws. The paw-pads are broad and very flat, with the whole undersurface of the foot around them being naked. The tail is relatively short, being 300–350 mm (12–14 in) long, and resembles a pompom in appearance. Unusually among hyaenids, and mammals in general, the female spotted hyena is considerably larger than the male. Both sexes have a pair of anal glands which open into the rectum just inside the anal opening. These glands produce a white, creamy secretion which is pasted onto grass stalks by everting the rectum. The odour of this secretion is very strong, smelling of boiling cheap soap or burning, and can be detected by humans several metres downwind. The spotted hyena has a proportionately large heart, constituting close to 1% of its body weight, thus giving it great endurance in long chases. In contrast, a lion's heart makes up only 0.45–0.57 percent of its body weight. The now extinct Eurasian populations were distinguished from the modern African populations by their shorter distal extremities and longer humerus and femur. The skull of the spotted hyena differs from that of the striped hyena by its much greater size and narrower sagittal crest. For its size, the spotted hyena has one of the most powerfully built skulls among the Carnivora. The dentition is more dual purposed than that of other modern hyena species, which are mostly scavengers; the upper and lower third premolars are conical bone-crushers, with a third bone-holding cone jutting from the lower fourth premolar. The spotted hyena also has its carnassials situated behind its bone-crushing premolars, the position of which allows it to crush bone with its premolars without blunting the carnassials. Combined with large jaw muscles and a special vaulting to protect the skull against large forces, these characteristics give the spotted hyena a powerful bite which can exert a pressure of 80 kgf/cm2 (1140 lbf/in²), which is 40% more force than a leopard can generate. The jaws of the spotted hyena outmatch those of the brown bear in bonecrushing ability, and free ranging hyenas have been observed to crack open the long bones of giraffes measuring 7 cm in diameter. A 63.1 kg (139 lb) spotted hyena is estimated to have a bite force of 565.7 newtons at the canine tip and 985.5 newtons at the carnassial eocone. One individual in a study was found to exert a bite force of 4,500 newtons on the measuring instruments.