Around 54 to 38 million years ago a new line of meat-eating mammals evolved. They became known as the carnivores and were distinct from all other meat eaters for the fact they possessed a unique feature – four carnassial teeth. Only carnivorous mammals possess teeth that adapted from a crushing chewing mechanics to a tearing and ripping mechanism facilitating cutting through flesh.
Modern day carnivores are believed to have evolved from two separate ancestral lines at some point:
1. Hesperocyon which habited North America 38-26 million years ago. This was perhaps the first genus to have developed an inner-ear anatomy a feature characteristic of the canine family.
2. Amphicyon which dominated the Eurasian continent for millions of years inter-lapping the same time frame as Hesperocyon. However somewhere along the line it is believed that the Amphicyon line died out.
Around 26-7 million years ago during the Miocene era Hesperocyon evolved into 42 different genera of canines with dog-like features of which Leptocyon (12 million years ago) an evolutionary descendant of Hesperocyon eventually evolved into the Canidae from whence came the modern canids which include wolves, foxes, jackals, coyotes and of course dogs.
Interestingly enough up until 10-20 million years ago bears and dogs were actually members of the same family before their evolution diverged to continue along separate paths. The ancestors of dogs are known to have evolved in response to climatic changes as well as changes to the environment. As tropical forests were superseded by vast areas of wide open savannah and steppes, so came into being the large herds of herbivores that are still present today in Africa.
Where beforehand the dog may have been a solitary hunter with the change in the environment it became expedient for the dog to evolve into a pack animal with a well formed social stratum. In this way dogs were able to successfully hunt and tackle the much larger prey that was characteristic of the grazing herds of herbivore. This pack mentality is still evident in the domestic dog as witnessed by roving packs of stray dogs in urban areas.
It is this innate ability of dogs to develop social relationships (inherited from wolves from which the domestic dog was bred) that is the basis of their success as a species!
Article on dog evolution written by Kayye Nynne