The Dire Wolf (Canis dirus) is an extinct member of the genus Canis (which contains the other wolves, the Coyote, jackals, and the other canines), and was most common in North America during the Pleistocene. Although it was closely related to the Gray Wolf, it was not the direct ancestor of any species known today. The Dire Wolf co-existed with the Gray Wolf in North America for about 100,000 years. They were one of the abundant Pleistocene megafauna-a wide variety of very large mammals that lived during the Pleistocene. Approximately 10,000 years ago, the Dire Wolf became extinct along with most other North American megafauna.

The first specimen of a Dire Wolf was found by Francis A. Linck at the mouth of Pigeon Creek along the Ohio River near Evansville, Indiana in 1854, but the vast majority of fossils recovered have been from the La Brea Tar Pits in California.

http://en.wikipedia.org/wiki/Dire_Wolf