The fascinating anatomy of the African wild dog

This text was written for the Newsletter Painted Dog Conservation: Dog Call 12, 144.

The African wild dog (Lycaon pictus) occupies an ecological niche characterized by hypercarnivory and cursorial hunting and differentiate from other canine species by their anatomical adaptations related this niche. A few of these adaptations are the narrowness of the canines and proportionately large premolars, which are the largest relative to body size of any carnivore other than hyenas. The heel of the first lower molars, that contain sharp edges for cutting flesh, are crested with a single, blade-like cusp. This special feature is called a ‘trenched heel’. Remarkably, the African wild dog shares this feature with the Asian wild dog (Cuon alpinus) from Asia and the bush dog (Speothos venaticus) from South America. These three species, from three different continents, are not closely related. They all evolved the trenched heel separate from each other, because all three species occupy a hypercarnivorous niche in which prey need to be consumed in speed. This is a great example of convergent evolution. There is also a difference in dentition between male and female African wild dogs. Females have relatively larger postcanine teeth to match the higher masticatory demands when they need to consume more food during lactation and pregnancy.

The skull of the African wild dog is relatively shorter and broader than those of other canids. When you look very closely to a wild dog skull, you might notice that the bony part of the ear canal called the external auditory meatus have a wide opening when you compare it to a canid of a similar size, like a grey wolf (Canis lupus) from a temperate region, but not as extreme as those of a fennec fox (Vulpes zerda) that inhabits deserts. The size of the external auditory meatus correlates with the size of the ears, which are adapted to the temperatures of the climate in which the species lives. African wild dogs are known for their outsized ears, that helps them cool down in the hot African climate and improves their hearing for hunting prey as an extra advantage. As mentioned, the African wild dog is also characterized by its cursorial hunting. For this ability, the wild dog possesses a graceful long-legged skeleton and the species’ forefeet lost its first digit, the dewclaw, during evolution to increases its stride and speed. This adaptation allows it to pursue prey across open plains for long distances. The evolution of the African wild dog is poorly understood due to the scarcity of fossil finds. Some have proposed that the genus Xenocyon should be reclassified as Lycaon. The species Xenocyon falconeri shared the African wild dog's absent dewclaw, though its dentition was still relatively unspecialised. Another ancestral candidate is the species Lycaon sekowei on the basis of its specialized dentistry including the trenched heel, but this species had not yet lost its dewclaw. The African wild dog sure is special to have specialized all these features that make them very successful predators.