Canidae

Lore & Background

The Canidae first appeared in North America during the Late Eocene. They did not reach Eurasia until the Late Miocene or South America until the Late Pliocene. The earliest identifiable member of the dog family, Prohesperocyon wilsoni, has been found in southwest Texas and dates to around 40 Mya. Canidae soon divided into three subfamilies during the Eocene: Hesperocyoninae, Borophaginae, and Caninae. By the Oligocene, all three subfamilies had appeared in the fossil record of North America. The earliest and most primitive branch was Hesperocyoninae, which included the coyote-sized Mesocyon. Around 8 Mya, the Beringian land bridge allowed members of the genus Eucyon to enter Asia from North America and colonize Europe. The Canis, Urocyon, and Vulpes genera developed from canids in North America. Around 5 million years ago, some Old World Eucyon evolved into the first members of Canis. The formation of the Isthmus of Panama about 3 Mya allowed canids to invade South America, where they diversified.

Reader's Guide

The Canidae family represents a significant group of carnivorans that have adapted to diverse habitats including forests, tundra, savannas, and deserts throughout tropical and temperate parts of the world. Modern canids include some 37 species ranging in size from the 2-metre-long gray wolf to the 24-centimetre-long fennec fox. Their body forms are similar, typically having long muzzles, upright ears, teeth adapted for cracking bones and slicing flesh, long legs, and bushy tails. They are mostly social animals, living together in family units or small groups and behaving co-operatively. One canid, the domestic dog, originated from a symbiotic relationship with Upper Paleolithic humans and is one of the most widely kept domestic animals. The evolutionary relationships between species have been studied using morphological and molecular approaches. In some species, genetic divergence has been suppressed by high levels of gene flow and hybridization. The family's history includes multiple colonizations of Africa from Eurasia during the Pliocene and Pleistocene, and the formation of the Isthmus of Panama allowed canids to diversify in South America.

Did You Know?

• Canids are found on all continents except Antarctica.
• The family includes three subfamilies: Caninae, and the extinct Borophaginae and Hesperocyoninae.
• The earliest identifiable canid, Prohesperocyon wilsoni, has been found in southwest Texas.
• The domestic dog originated from a symbiotic relationship with Upper Paleolithic humans.