dire wolf

Canis dirus (Dire Wolf) Fossil range: Early Pleistocene–Late Pleistocene PreЄ Є O S D C P T J K Pg N ↓
Skeleton in the George C. Page Museum at the La Brea Tar Pits, Los Angeles
Scientific classification
Domain:	Eukarya
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Canidae
Genus:	Canis
Species:	†C. dirus
Binomial name
†Canis dirus Leidy, 1858
Range of Dire Wolf based on fossil distribution
Synonyms
C. ayersi C. indianensis C. mississippiensis

Timeline of canids including Canis dirus in red. (Tedford & Wang)

The Dire Wolf, Canis dirus, is an extinct carnivorous mammal of the genus Canis, and was most common in North America and South America from the Irvingtonian stage to the Rancholabrean stage of the Pleistocene epoch living 1.80 Ma – 11,000 years ago, existing for approximately 1.79 million years.

Relationships

Restoration by Charles R. Knight

Although it was closely related to the Grey Wolf and other sister species, Canis dirus was not the direct ancestor of any species known today. Unlike the Grey Wolf, which is of Eurasian origin, the Dire Wolf evolved on the North American continent, along with the Coyote.^[1] The Dire Wolf co-existed with the Grey Wolf in North America for about 100,000 years.

The Dire Wolf was 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 most fossils recovered have been from La Brea Tar Pits in California.

Taxonomy

Canis dirus was named by Joseph Leidy in 1858 and recombined as Aenocyon dirus by Merriam (1918), Hibbard (1949) and Hibbard and Taylor in 1960. In 1916, Canis ayersi was named by Sellards. It was recombined as Aenocyon ayersi by Merriam in 1918 and was synonymized subjectively with C dirus by Lundelius in 1972^[2], Martin (1974), Nowak (1979), Kurten and Anderson (1980) and Kurten in 1984.^[3] Leidy also named the Dire wolf as Canis indianensis in 1869 which was synonymized subjectively with C. dirus by Troxell in 1915.^[4] Canis mississippiensis was named by Allen in 1876 and synonymized subjectively with Canis dirus by Nowak (1979), Kurten and Anderson (1980) and again by Kurten in 1984.^[5]

Morphology

Body mass and dimensions

The Dire Wolf was larger than the Grey Wolf, averaging about 1.5 metres (5 ft) in length and weighing about 57 kg (130 lb) – 87.9 kg (190 lb).^[6][7] Despite superficial similarities to the Grey Wolf, there were significant differences between the two species. The legs of the Dire Wolf were proportionally taller and sturdier than those of the Grey Wolf, and its brain case was smaller than that of a similarly-sized grey wolf.^[8]

Dentition

The Dire Wolf's teeth were similar to the Grey Wolf's, only slightly larger pointing to a hypercarnivorous to mesocarnivorous activity. Paleontologist R.M. Nowak states the dietary characteristics are primarily carnivorous as well as partially omnivorous.^[9]

Many paleontologists have proposed 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 their fossilized teeth. The upper carnassials had a much larger blade than that of the Grey Wolf, indicating greater slicing ability. It had a longer temporal fossa and broader zygomatic arches, indicating the presence of a large temporalis muscle capable of generating slightly more force than a Grey Wolf's.^[10] However, other scientists have noted that the dorsoventral and labiolingual force profiles are indistinguishable from those of other canids such as coyotes and African wild dogs, indicating a similar diet.^[11] Dire wolf teeth lacked the craniodental adaptations of habitual bonecrushers such as hyenas and borophagines.^[10] The dorsoventrally weak symphyseal region indicates it killed in a manner similar to its modern relatives, by delivering a series of shallow bites, strongly indicating pack hunting behaviour. However, the incidence of broken post-carnassial molars is much higher than in fossil Grey Wolves, indicating that the species was probably less adapted to bone crushing than the Grey Wolf.^[11]

Evolution and extinction

Artistic rendition of 2 possible appearances of the dire wolf, one based on a North American origin and the other on a possible South American origin

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 (Ma) ago, along with two other genera, Urocyon, and Vulpes. Canids soon spread to Asia and Europe (8 Ma BP) and became the ancestors of modern wolves, jackals, foxes, and the Raccoon Dog. By 3–5 Ma BP, canids had spread to Africa (Early Pliocene) and South America (Late Pliocene). Their invasion of South America as part of the Great American Interchange was enabled by the formation of the Isthmus of Panama 3 Ma ago.

From C. armbrusteri

Over the next nine million years, extensive development and diversification of the North American wolves took place by the Middle Pleistocene. Canis ambrusteri appeared and there is good evidence that Dire Wolf evolved from C. armbusteri with the two taxa sharing in the open plains and grasslands of the central United States. C. dirus eventually displaced C. armbrusteri with its last years remaining in the southeastern U.S., more specifically Florida. While this occurred, C. dirus expanded its range to include that of C. Armbrusteri and move into Central America and South America appearing in the Late Pleistocene fossil record in northwestern South America.^[12]

During the Late Pleistocene (300,000 years ago) the Grey Wolf (Canis lupus) crossed into North America on the Bering Strait land bridge and competed with Dire Wolf. Starting about 16,000 years ago, coinciding with the end of the last glacial period and the arrival of humans in North America, most of the large mammals upon which the Dire Wolf depended for prey began to die out (possibly as a result of climate and/or human-induced changes). 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, the large mammals and the Dire Wolf were extinct.

Fossil record

A display of some of the thousands of Dire Wolf skulls found in La Brea tar pits

The Dire Wolf is best known for its unusually high representation in La Brea Tar Pits in California. Fossils from more than 3,600 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.

Evansville Dire Wolf

The type specimen of the Dire Wolf was found in Evansville, Indiana in the summer of 1854, when the Ohio River was quite low. The specimen, a fossilized jawbone, was obtained by Joseph Granville Norwood from an Evansville collector named Francis A. Linck. Norwood, who at that time was the first state geologist of Illinois, sent the specimen to Joseph Leidy at the Academy of Natural Sciences in Philadelphia.^[13] Leidy determined that the specimen represented an extinct species of wolf and published a note to that effect in November 1854.^{[citation needed]} In a publication dated 1858, Leidy assigned the name Canis dirus.^{[citation needed]}

Norwood's letters to Leidy, as well as the type specimen itself, are preserved at the Academy of Natural Sciences although one of the letters indicates that the specimen was to be returned to Linck's family, as Linck himself died in August 1854.

See also

• List of extinct animals
• Alsatian Shepalute A new breed of dog bred to resemble the Dire Wolf's size and bone structure.

References

External links

Wikispecies has information related to: Canis dirus

Wikimedia Commons has media related to: Canis dirus

• The Evansville Dire Wolf
• Information on the dire wolf from the Illinois State Museum
• Return to the Ice Age: The La Brea Exploration Guide
• Chronology of wolf evolution
• Academy of Natural Sciences: dire wolf
• WolfSource
• Western Center for Archaeology and Paleontology Hemet, CA

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