How long have dogs existed?

The first dog-like mammal that appeared on Earth evolved during the Eocene Epoch, about 50 million years ago. The dog family (wolves/domestic dogs, foxes, jackals, coyotes, etc.) are closely related to turtles, and other amphibious creatures, including frogs and newts. This accounts for the disappearences of dogs for long periods of time, as they are mearly returning to their ancestual habitat, under the water.