The Dire Wolf

[Barry the Baryonyx]

The Dire Wolf

_{© Mark Hallet}


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, as commonly assumed, 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. Circa 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 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.

Characteristics


Dire Wolves were significantly larger than the Gray Wolf, the largest living wild canid; they averaged about 2.1 metres (7 feet) in length and weighed about 63-91 kilograms (138-200 pounds). Gray Wolves, by contrast, usually range between 23–59 kilograms (50–130 pounds), so a large modern wolf would be about the same size as a small Dire Wolf.

Despite superficial similarities in appearance, there were significant differences between the two species. The legs of the Dire Wolf were proportionally shorter and sturdier than those of the Gray 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 Gray 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 to 10 million years ago (Ma), along with two other genera, Urocyon, and Vulpes. Canids soon spread to Asia and Europe (8 Ma) and become the ancestors of modern wolves, jackals, foxes, and the Raccoon Dog. By 4 Ma – 5 Ma, 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 Gray Wolf (Canis lupus) crossed into North America via the Bering Strait land bridge. By 100,000 years ago the Dire Wolf 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 Wolf depended for prey began to die out (possibly as a result of human-induced changes). Slower than the other wolf species on the continent at the time, primarily the Gray 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, the large mammals and the Dire Wolf were extinct, although some fossils found in Arkansas suggest that they may have lived as a relic population 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 California. 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 the Dire Wolf, 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.[/i][/color]

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