Caninae

Caninae is the only subfamily of canids with living members; the other two subfamilies, Borophaginae and Hesperocyoninae, are extinct. Animals in this group are called canines. They first evolved in North America about 35 million years ago, during the Oligocene, and later spread to Asia and the rest of the Old World roughly 7 to 8 million years ago, near the end of the Miocene.

The first primitive canine was the genus *Leptocyon*, which contained 11 species. These animals were small, weighing about 2 kilograms, and first appeared in what is now Sioux County, Nebraska, around 34 to 32 million years ago, at the start of the Oligocene. This was the same time the Borophaginae appeared, and the two groups share features, suggesting they are sister groups. Unlike the Borophaginae, whose skulls and teeth were built for a powerful killing bite, *Leptocyon* was adapted for snatching small, fast-moving prey. One species, *L. delicatus*, is the smallest canid ever known. By the time the genus died out 9 million years ago, one lineage of *Leptocyon* resembled modern foxes. The various *Leptocyon* species split into two branches 11.9 million years ago: the Vulpini (foxes) and the Canini (canines).

Canines spent about two-thirds of their evolutionary history in North America before dispersing into Asia, Europe, and Africa around 7 million years ago. One trait that set them apart from the Borophaginae and Hesperocyoninae was having lighter limbs and longer legs, which may have helped them spread. The first canine to reach Eurasia was the coyote-sized *Canis cipio*, known from a few fossils found in Spain. However, it is unclear whether *C. cipio* belongs to the genus *Canis* or *Eucyon*.

Genetic analyses, including allozyme and chromosome studies, have suggested several phylogenetic divisions. DNA evidence shows that the first three groups form monophyletic clades. The wolf-like canines and the South American canines together make up the tribe Canini. Molecular data indicate that living Canidae originated in North America about 10 million years ago, and that wolf-like canines (including *Canis*, *Cuon*, and *Lycaon*) originated in Africa, with jackals being the most basal members of this group. The South American clade is rooted by the maned wolf and bush dog, while the fox-like clade is rooted by the fennec fox and Blanford's fox. The gray fox and island fox are basal to the other clades, though this arrangement is not strongly supported. A cladogram based on the phylogeny of Lindblad-Toh (2005), modified with recent findings on *Canis*, *Vulpes*, *Lycalopex*, and *Dusicyon*, illustrates these relationships.