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Dire Wolf
The dire wolf (Canis dirus) is an extinct member of the genus Canis (wolves, coyotes, jackals, and domestic dogs), 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. Dire wolves 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 dire wolf fossils recovered have been from the La Brea Tar Pits in California (about 3,600). Characteristics The common misconception of the dire wolf is that it was much larger than the grey wolf. In truth, the dire wolf was similar in overall size and appearance to a large grey wolf. On average it was about 1.5 metres (5 feet) in length and weighed about 50 kilograms (110 pounds). Despite superficial similarities, there were significant differences between the dire wolf and grey wolf. The legs of the dire wolf were proportionally shorter and sturdier than those of the grey wolf, which suggests that the dire wolf was not as good of a runner as the grey wolf. This suggests that, like the hyenas, the dire wolf may have scavenged for food and/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, raccoon dogs, and 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 takes place, and by the Mid-Pleistocene (800,000 years ago) Canis ambrusteri appears and spreads across North and South America. Soon it disappears from North America, but probably continues to survive in South America to become the ancestor of the dire wolf, Canis dirus. (There is some other evidence that Canis dirus may have arose instead from other small South American wolves.) During the Late Pleistocene (300,000 years ago) the grey wolf (Canis lupus) crosses into North America via the Bering Strait land bridge. By 100,000 years ago dire wolves also appear in North America (probably from South America). Starting about 16,000 years ago, coinciding with the end of the 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. Slower than the other wolf species on the continent at the time, primarily the grey wolf (Canis lupus) and red wolf (C. rufus), they could not hunt the swifter species that remained and were forced to subsist on scavenging. By 10,000 years ago, both the large mammals and dire Wolves were completely 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 large presence 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
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