Figure 1. Body plan of a carnivore showing dental and skeletal specializations for a predatory lifestyle. (From Macdonald (1984), with permission.) (a) The skull of a carnivore as exemplified by the grey wolf. (b) Carnassial teeth, the key feature of the order Carnivora. The sharp tips, high cusps and jagged edges of the last upper premolar and the first lower molar fit together perfectly to provide a shearing surface to cut flesh. (c) Skeleton of the grey wolf. Most carnivores have a powerful, agile body and a strong skeleton. In addition to the modified clavicle, dentition and wrist, the ulna and fibula (usually the more slender of two bones in mammals’ front and rear lower limbs respectively) are well developed as an adaptation to the swift pursuit of prey that characterizes members of the dog family; the radius and ulna of the front legs are locked together to prevent rotation. (d) Fused wrist bones are typical of carnivores in which the scaphold, lunar and centrale bones are fused together to form the scapholunar bone. (e) The collar bone is reduced in all carnivores. Shown here is the collar bone (clavicle) of a wolf which is reduced to a mere sliver of bone suspended on ligaments. (f) Jaw power is crucial for the capture and tearing-up of prey. Shown here are the lines of force exerted by the jaw-closing muscles of the dog. The massive temporalis (t) delivers the power to exert suffocating or bone-splitting pressure even when the jaws are agape; the rearmost (posterior) fibres of the muscle are most effective when the jaws are open wide. The masseter muscle (m) provides the force needed to cut flesh and for grinding when the jaws are almost closed.

Figure 2. Phylogeny of the Carnivora. (After Van Valkenburgh (1999) Major patterns in the history of carnivorous mammals. Annual Reviews in Earth and Planetary Sciences 27: 463–493. With permission.)