Giant Cheetah - Morphology

Morphology

The lifestyle and physical characteristics of the giant cheetah were probably similar to that of its modern relative, except that the giant cheetah was the height of a lion at the shoulder (but, due to its light build, it weighed considerably less than a lion). It was roughly twice the size of today's cheetahs, putting it at around 120 kilograms (260 lb), and about 200 centimetres (79 in) from head to rump, not including a 140 centimetres (55 in) tail. Its reconstructed shoulder height was at 90 centimetres (35 in). It was a specialized sprinter with long limbs just like the modern cheetah and a back that was slightly longer. This back was highly flexible and allowed great propulsion during a sprint.

Just as with the modern cheetah, almost every aspect of Acinonyx pardinesis was specialized for running. The muzzle is short, nasal passage large for increased air intake during a strenuous sprint. To make room for the enlarged nasal passage, the maxilla was reduced and the anchorage for the canine roots was less, resulting in shorter canine roots and a shorter, more stout external canine, a characteristic seen in the modern cheetah. To lighten the weight of the animal, bone girth is reduced and the skeleton is lean and light, excellent for running but not fighting or coping with injuries, severe or minor. Its thoracic cavity was consumed by large lungs and a powerful heart. The intestines were probably shorter, to lighten the animal, and muscles not used for running were reduced. The diaphragm was connected to the movement of its gait and with the stretching phase of a stride, the expansion of space in the abdominal cavity pulled the diaphragm down and forced the animal to inhale, while the contractile phase compressed the lungs and forced air out, so it had no control over its breathing while running, a commonality of most quadruped sprinters. It was a fragile animal that could be killed by a simple sprain (if it meant the individual could not run well enough to hunt). Its tail was long, probably thickly furred, and relatively heavy; it was used as a counterweight to aid in quick directional changes when chasing prey.

One of the most complete skulls of this species is from the well-known French site of Saint-Vallier, but the best collection of postcranial bones came from the older site of Perrier in the Massif Central, including vertebral column and long bones of one individual were found. Unfortunately, the metacarpals were not recovered and so subsequent reconstructions depict them at the same length as the modern Acinonyx.