Dire Wolf
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| Dire Wolf Conservation status: Fossil | ||||||||||||||
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| Missing image Dire_Wolf.jpg Dire Wolf fossils at the National Museum of Natural History, Washington, DC | ||||||||||||||
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| Canis dirus Leidy, 1858 |
The Dire Wolf (Canis dirus) is an extinct member of the genus Canis (which contains the wolves, Coyote, jackals, and the Domestic Dog), and was most common in North America during the Pleistocene. Although it was closely is related to the Grey Wolf and hyenas, it was not, as commonly assumed, the direct ancestor of any species known today. The Dire Wolf co-existed with the Grey Wolf in North America for about 100,000 years, until its extinction about 10,000 years ago during a time of mass extinction of many large North American mammals.
The first specimen of a Dire Wolf was found by Francis Lick on the banks of 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.
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Characteristics
The common misconception of the Dire Wolf is that it was much larger than the Grey Wolf; in fact it was similar in overall size and appearance. On average it was a little larger at about 1.5 metres (5 feet) in length and about 50 kilograms (110 pounds). Despite superficial similarities, there were significant differences between the two species.
The legs of the Dire Wolf were proportionally shorter and sturdier than those of the Grey Wolf, which suggests that the Dire Wolf was a poorer runner, and that like the hyenas, the Dire Wolf may have scavenged for food or hunted large, slower-moving prey.
The Dire Wolf had a larger, broader head and smaller brain-case than that of a similarly-sized Grey Wolf, and had teeth that were quite massive. Many paleontologists think that the Dire Wolf may have used its relatively large teeth to crush bone, an idea that is supported by the frequency of large amounts of wear on the crowns of fossilized dire wolf teeth.
Evolution and Extinction
The fossil record suggests that the genus Canis diverged from the small, foxlike Leptocyon in North America sometime in the Late Miocene Epoch (9 MYA - 10 MYA), along with two other genera, Urocyon, and Vulpes. Canids soon spread to Asia and Europe (8 MYA) and become the ancestors of modern wolves, jackals, foxes, and Raccoon Dogs. By 4 MYA - 5 MYA, canids spread to Africa (Early Pliocene) and South America (Late Pliocene).
Over the next nine million years, extensive development and diversification of the North American wolves took place, and by the Mid-Pleistocene (800,000 years ago) Canis ambrusteri appeared and spread across North and South America. It soon disappeared from North America, but probably continued to survive in South America to become the ancestor of the Dire Wolf. (However there is some evidence to suggest that the Dire Wolf may have arisen from other small South American wolves.)
During the Late Pleistocene (300,000 years ago) the Grey Wolf (Canis lupus) crossed into North America via the Bering Strait land bridge. By 100,000 years ago Dire Wolves also appeared in North America (probably from South America).
Starting about 16,000 years ago, coinciding with the end of the most recent Ice Age and the arrival of humans on the North American continent, most of the large mammals upon which the Dire Wolves depended upon for prey began to die out (probably largely as a result of human-induced changes, but this remains uncertain). Slower than the other wolf species on the continent at the time, primarily the Grey Wolf and Red Wolf, it could not hunt the swifter species that remained and was forced to subsist on scavenging. By 10,000 years ago, both the large mammals and Dire Wolves were extinct, although some fossils found in Arkansas suggest that they may have lived in the Ozark mountains as recently as 4,000 years ago.
La Brea Tar Pits
The Dire Wolf is best known for its unusually high representation in the La Brea Tar Pits. In total, fossils from more than 3,600 individual Dire Wolves have been recovered from the tar pits, more than any other mammal species. This large number suggests that Dire Wolves, like modern wolves and dogs, probably hunted in packs; it also gives some insight into the pressures placed on the species near the end of its existence.
External links
- Information on the dire wolf from the Illinois State Museum (http://www.museum.state.il.us/exhibits/larson/canis.html)
- Return to the Ice Age: The La Brea Exploration Guide (http://www.tarpits.org/education/guide/flora/wolf.html)
- Chronology of wolf Evolution (http://www.searchingwolf.com/wevolve.htm)
- National Academy of Sciences: dire wolf (http://www.acnatsci.org/museum/leidy/paleo/canis.html)nl:reuzenwolf