Canids are mammals characterized by pointed canines (developed for an omnivorous diet) and a skeleton built for a mode of walking or running called digitigrade (walking on the toes without the heels touching the ground).
They belong to the Carnivora order, which developed in the early Tertiary Era in ecological niches abandoned by large reptiles that disappeared at the end of the Mesozoic Era.
At that time, they began to spread throughout North America and diversify with the appearance of a Carnivora family-Miacidae-which resembled the modern-day weasel. Miacids (a family which included forty-two different genera) flourished forty million years ago; today, only sixteen genera remain. The modern Canid family includes three sub-families: Cuoninae (Lycaon), Otocyoninae (South African Otocyon), and Caninae (dog, wolf, fox, jackal, coyote).
Evolution of Canids
Canids gradually replaced Miacids, giving rise to the Hesperocyon genus, which was very common approximately thirty-five million years ago. Their skull and toes showed skeletal and dental features similar to those of modern-day wolves, dogs, and foxes, indicating a direct link to these early carnivores.
During the Miocene, the Phlaocyon genus appeared. It is thought to have resembled a raccoon. The teeth of the Mesocyon genus, which also developed at that time, were similar to those of modern dogs.
The body profile of Canids evolved through the Cynodesmus (which looked like a coyote), the Tomarctus, and the Leptocyon, gradually taking on the appearance of today's wolf or even Spitz-type dogs with the loosening of the curl of the tail, the lengthening of the legs and extremities, and the diminution of the fifth toe (dewclaw), which allowed the animal to run more quickly.
Rise of the Canis Genus
Canis Canids did not appear until the end of the Tertiary Era. They crossed the Bering Strait and reached Europe during the late Eocene, but seemed to disappear during the early Oligocene as Ursids (bears) grew in numbers. In the late Miocene, Canis lepophagus migrated to Europe from North America. This new arrival looked much like modern dog, though was closer to the size of a coyote.
During the Pliocene, these Canids spread toward Asia then Africa. Ironically, they apparently did not move into South America until much later, during the early Pleistocene.
Finally, humans introduced the genus to Australia around 500,000 years ago, during the late Pleistocene. However, there is no proof that these early Canids gave rise to the Dingo-modern-day wild dogs that were brought to Australia a mere 15,000 to 20,000 years ago.
Ancestor of the Wolf; Jackal, and Coyote
Canis etruscus (Etruscan dog) appeared approximately one to two million years ago. Despite its smaller size, it is thought to be the ancestor of European wolves. Canis cypio, which lived in the Pyrenees eight million years ago, seems to be the ancestor of modern jackals and coyotes.
Importance if Archeological Sites in Europe and China
Several varieties of dogs have been found at European archeological sites. The largest are thought to be descended from the large northern wolves which stood as tall as the withers of today's Great Dane. They probably gave rise to Nordic dogs and large herders. The smaller dogs, morphologically similar to modern-day wild Dingos, are likely descended from smaller wolves from India or the Middle East.
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