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Dire wolf

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Dire wolf
Temporal range: Early Pleistocene - Holocene, 1.8–0.010 Ma
Mounted skeleton
Scientific classification
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
C. dirus
Binomial name
Canis dirus
Leidy, 1858
Synonyms
  • C. ayersi
  • C. indianensis
  • C. mississippiensis
  • Aenocyon dirus

The dire wolf (Canis dirus "fearsome dog") is an extinct carnivorous mammal of the genus Canis, roughly the size of the extant gray wolf, but with a heavier build. It 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—10,000 years ago, persisting for approximately 1.79 million years.

Morphology

The skull of the Dire wolf

The dire wolf averaged about 1.5 m (4.9 ft) in length and weighed between 50 kg (110 lb) and 79 kg (174 lb).[1] Limb elements are rarely found outside the la Brea tar pits, which makes it hard to compare the size of average individuals between populations. The dire wolf is estimated to have been 8% smaller than the modern timber wolf, and of equal size to the gray wolf, but heavier built.[2] With the exception of the canine teeth in some populations, male and female body and teeth sizes evidence no major sexual dimorphism, similar to most canines. In some populations, males’ canines were considerably larger, implying male competition for breeding access. In other populations, lack of dimorphism in the canine teeth implies little competition.[3]

Despite superficial similarities to the gray wolf, the two species differed significantly. Wolves of Late Pleistocene are genetically unique and morphologically distinct. None of the 16 mtDNA haplotypes recovered from a sample of 20 Pleistocene eastern-Beringian wolves was shared with any modern wolf. Instead, they appear most closely related to Late Pleistocene wolves found in Eurasia[4] . Today’s largest gray wolves would have been of similar size to an average dire wolf; the largest dire wolves would have been considerably larger than any modern gray wolf. The dire wolf is calculated to weigh 25% more than living gray wolves.[2]

Many of these characteristics were needed to fight off and prey on larger megafauna.[5] The legs of the dire wolf were proportionally shorter and sturdier than those of the gray wolf, and its brain case was smaller than that of a similarly sized gray wolf.[6]

Dentition

The large body size and highly carnivorous dentition that is characteristic of C. dirus has stimulated much debate regarding preferred prey and other aspects of its feeding and hunting behavior.

The dire wolf's teeth were similar to the gray wolf's, only slightly larger, pointing to a hypercarnivorous to mesocarnivorous activity. The dietary characteristics were primarily carnivorous, as well as partially omnivorous.[7]

Between C. lupis and C. dirus, C. lupis had a significantly greater mechanical advantage of the temporalis muscle over C. dirus at the lower carnassial and P4 (MATM1, MATP4).[8]

The slicing teeth (P4, the carnassial) on the upper jaw of C. dirus are larger than those of the gray wolf, but those on the lower jaw are similar. The temporalis of the dire wolf could generate more force than seen in modern gray wolves, suggesting stronger killing bites.[9]

Many paleontologists have proposed that the dire wolf may have used its relatively large teeth to crush bone, an idea supported by the frequency of large amounts of wear on the crowns of their fossilized teeth. The upper carnassial had much larger blade than that of the gray 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 gray wolf's.[10] However, other scientists have noted 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 postcarnassial molars is much higher than in fossil gray wolves, indicating the species was probably less adapted to bone crushing than the gray wolf.[11]

Behavior and ecology

Restoration of a pack by Charles R. Knight, 1922

Dire wolves are part of the same carnivorous guild as the smaller gray wolves and coyotes.[12] Dire wolves' overpowering bite, 129% of the force of the modern gray wolf, could hold and subdue their prey. As inferred from their large bodies and carnivorous teeth, they often took on large prey or megafauna, made possible by traveling in packs. Dire wolves were not specialized hunters—they fed on whatever megafauna was abundant.[13]

Compared to modern species, a remarkable number of dire wolf specimens from the La Brea pits showed evidence of having broken their teeth in life. Specimens in the older part of the pit exhibited more tooth wear than those in the younger pit, which indicates a difference in diet between these periods. Carcasses and bones were consumed more frequently in the earlier period than later.[14]

Habitat and distribution

The habitat of C. dirus varied considerably. In North America, it ranged from plains and grasslands to forested mountain areas. In South America, it occupied areas characterized by arid savannah conditions and dry weather.[10] The dire wolf lived in several different habitats, tropical marsh with thorn-scrub to deciduous forest including some component of nearby grassland, and from sea level up to 2255 m (7400 feet). It was geographically widespread, and its remains have been found in 136 different localities, ranging from Alberta, Canada, to Tarija, Bolivia.[15]

The dire wolf is well known for its unusually high representation in La Brea Tar Pits in California. Over 200,000 fragments representing more than 4,000 individual dire wolves have been recovered from the tar pits, more than any other mammal species.[2] This large number suggests the dire wolf, like modern wolves and dogs, hunted in packs. The abundance of remains of the gray wolf (C. lupus, also known as C. furlongi) in the tar pits is about one per cent that of the dire wolf.[16]


Material and Methods

In order to come to a conclusion as to what the body mass of the Canis Dirus weighed a test was conducted, collecting samples femora and comparing tese samples to other female and male dire wolves. One hundred femora of the extinct Pleistocene dire wolf, Canis dirus, from the Rancho La Brea deposits in southern California were measured for this study. Combined materials from California and Mexico sample the population of dire wolves in North American, Continental divide for which Kurten creates a subspecies Cains Dirus Guildya. Kurten then established a subspecies Canis Dirus Dirus to add to the eastern population. Hawksley and other paleontologist figured a complete femur of the dire wolf from Carroll Cave, Missouri, which measured 278.5 mm. long.

22 species of extant canids were used in this study. Ten femora were measured for each species and depending on availability, in equal numbers of males and females were observed. This was achieved by pooling specimens from three museum collections (FMNH, UCLA, and USNM). The mean body weights of the extant canids were obtained from the literature. Effort was made to match the weights published in the literature with known data that reflected the geographic variation in weight of each species. When mean weights for a species were not available, the mid-point of the minimum and maximum weights recorded in the literature was used as species means.

Data was used to explore the relationship between body mass (the dependent variable) and five femoral measures (length, circumference, cortical area) in the 22 species of extant canids. This sample comprised species with a mean bodymass ranging from 1.7 kg, similar to the sand fox, to 45 kg, more like the grey wolf.

Results after the experiment shoed that For the western dire wolves, the mean body mass estimates range from 34–67 kg. The Femora length is a poor predictor of body mass.[17]

Taxonomy

Display of some of the thousands of dire wolf skulls found in La Brea Tar Pits

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,[18] Martin (1974), Nowak (1979), Kurten and Anderson (1980) and Kurten in 1984.[19] Leidy also named the dire wolf as Canis indianensis in 1869 which was synonymized subjectively with C. dirus by Troxell in 1915.[20] 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.[21]

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.[22] 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.[23] Leidy determined the specimen represented an extinct species of wolf and published a note to that effect in November 1854.[22] In a publication dated 1858, Leidy assigned the name Canis dirus.[22]

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

Evolution

An artistic rendition of two possible appearances of the dire wolf, one based on a North American origin (left) and the other on a less plausible South American origin (right)

Whether the dire wolf originated in North America versus South America is the subject of controversy. Most paleontologists lean toward a North American origin for three reasons: first, more potential progenitors are present in the middle Pleistocene of North America; second, distribution of C. dirus is much better represented in North America, with 136 sites versus only three localities in South America;[24] and last, C. dirus appears earlier in the fossil record in North America than South America. A North American origin implies that C. dirus migrated into South America from North and Central America.[10]

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.

Over the next nine million years, extensive development and diversification of the North American wolves took place by the Middle Pleistocene. Canis armbrusteri appeared, possibly from C. chihliensis in Asia. There is good evidence that the dire wolf evolved from C. armbrusteri, with the two taxa sharing in the open plains and grasslands of what is now the central United States.[25]

C. dirus eventually displaced C. armbrusteri, with the latter's final range shrinking to what is now the southeastern U.S., more specifically Florida. While this occurred, C. dirus expanded its range to include that of C. armbrusteri and moved into Central America and South America, appearing in the Late Pleistocene fossil record in northwestern South America.[25]

Two subspecies of the dire wolf are known to have inhabited what is now the United States. C. dirus guildayi was smaller and ranged west of the Rocky Mountains. C. dirus dirus was larger and ranged east of the Rockies.[9]

Although it was closely related to the gray wolf and other sister species, C. dirus is not the direct ancestor of any modern species. Unlike the gray wolf, which is of Eurasian origin, the dire wolf evolved on the North American continent, along with the coyote.[26] The dire wolf co-existed with the gray wolf in North America for about 100,000 years.

Extinction

Two dire wolves mired in tar while fighting Smilodon over a Columbian mammoth carcass

The dire wolf was one of the abundant Pleistocene megafauna—a wide variety of large mammals that lived during the Pleistocene. Approximately 10,000 years ago the dire wolf became extinct along with most other North American megafauna.[27][28]

During the Late Pleistocene (300,000 years ago) the gray wolf (C. lupus) crossed into North America on the Bering Strait land bridge and competed with the 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 as suggested in a 2008 National Geographic Channel documentary[29]).

Slower than the other wolf species on the continent at the time, primarily the gray wolf and red wolf, the dire wolf could not hunt the swifter species that remained and was forced to subsist by scavenging. By approximately 10,000 years ago, the large mammals and the dire wolf were extinct. In order to fully understand the extinction of C. dirus, many more dire wolf specimens must be directly dated. In addition to this, more information must be gathered on the factors that affected its biogeographical range and population size, including competition, interactions with predators and prey, its physical environment, as well as how all of its competitors and prey responded to the event of time; thus, the timing of extinction of megafauna that closely interacted with C. dirus must be determined.[10]

See also

References

  1. ^ "Wolves, Coyotes, and Dogs (Genus Canis)". Museum.state.il.us. Retrieved 2011-10-23.
  2. ^ a b c Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1671/0272-4634(2006)26[209:NBMEFC]2.0.CO;2, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1671/0272-4634(2006)26[209:NBMEFC]2.0.CO;2 instead.
  3. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1671/0272-4634(2002)022[0164:SDSBAI]2.0.CO;2, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1671/0272-4634(2002)022[0164:SDSBAI]2.0.CO;2 instead.
  4. ^ Leonard, Jennifer. "Megafaunal Extinctions and the Disappearance of a Specialized Wolf Ecomorph". Current Biology. Cell Press. Retrieved 21 October 2013.
  5. ^ Hodnett, John-Paul; Mead, Jim I.; Baez, A. (2009). "Dire Wolf, Canis dirus (mammalia; Carnivora; Canidae), from the Late Pleistocene (Rancholabrean) of East-Central Sonora, Mexico". The Southwest Naturalist. 54 (1): 74–81. doi:10.1894/CLG-12.1. Retrieved 31 October 2012.
  6. ^ "Wolves, Coyotes, and Dogs (Genus Canis)". Illinois State Museum. Retrieved 2010-06-21.
  7. ^ R. M. Nowak. 1991. Walker's Mammals of the World. Maryland, Johns Hopkins University Press (edited volume) II
  8. ^ Anyonge, W. "Craniofacial morphology and feeding behavior in Canis dirus, the extinct Pleistocene dire wolf". Journal of Zoology. Retrieved 21 October 2013.
  9. ^ a b "Dire Wolf Fact Sheet". San Diego Zoo. Retrieved 31 October 2012.
  10. ^ a b c d e Anyonge, William (2006). "Craniofacial morphology and feeding behavior in C. dirus, the extinct Pleistocene dire wolf". Journal of Zoology. 269 (3): 309–316. doi:10.1111/j.1469-7998.2006.00043.x. {{cite journal}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  11. ^ a b Therrien, F. (2005). "Mandibular force profiles of extant carnivorans and implications for the feeding behaviour of extinct predators". Journal of Zoology. 267 (3): 249. doi:10.1017/S0952836905007430.
  12. ^ Leonard, Jennifer. "Megafaunal Extinctions and the Disappearance of a Specialized Wolf Ecomorph". Current Biology. Cell Press.
  13. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1098/rspb.2004.2986, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1098/rspb.2004.2986 instead.
  14. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1671/0272-4634(2002)022[0423:TVITFA]2.0.CO;2, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1671/0272-4634(2002)022[0423:TVITFA]2.0.CO;2 instead.
  15. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1502-3885.1999.tb00227.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1502-3885.1999.tb00227.x instead.
  16. ^ Stock, C. (1929-11). "A Census of the Pleistocene Mammals of Rancho La Brea, Based on the Collections of the Los Angeles Museum". Journal of Mammalogy. 10 (4): 281–289. JSTOR 1374112. Retrieved 2013-01-27. {{cite journal}}: Check date values in: |date= (help)
  17. ^ Hodnet, John Paul (2009). "DIRE WOLF, CANIS DIRUS (MAMMALIA; CARNIVORA; CANIDAE), FROM THE LATE PLEISTOCENE (RANCHOLABREAN) OF EAST-CENTRAL SONORA, MEXICO". 54.1: 74-81. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  18. ^ E. L. Lundelius. 1972. Bureau of Economic Geology Report of Investigations 77
  19. ^ J. C. Merriam. 1918. University of California Publications, Bulletin of the Department of Geology
  20. ^ E. L. Troxell. 1915. American Journal of Science 189
  21. ^ B. Kurten. 1984. Carnegie Museum of Natural History Special Publication 8
  22. ^ a b c "Canis dirus 1854". Academy of Natural Sciences. Retrieved June 6, 2010.
  23. ^ Kimberling, Clark (March 1996). "David Dale Owen and Joseph Granville Norwood: Pioneer Geologists in Indiana and Illinois". Indiana Magazine of History (62): 2–25.{{cite journal}}: CS1 maint: date and year (link)
  24. ^ "Canis dirus (dire wolf)". Paleobiology Database. Retrieved 2013-01-27.
  25. ^ a b Tedford, Richard H.; Wang, Xiaoming; Taylor, Beryl E. (2009). "Phylogenetic systematics of the North American fossil Caninae (Carnivora, Canidae)" (PDF). Bulletin of the American Museum of Natural History. 325: 218. doi:10.1206/574.1. hdl:2246/5999.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  26. ^ "Statement by Valerius Geist pertaining to the death of Kenton Carnegie" (PDF). Wolf Crossing. Retrieved 2008-09-09. [dead link]
  27. ^ Marc Zabludoff (September 2009). Dire Wolf. Marshall Cavendish. pp. 24–27. ISBN 978-0-7614-3998-1. Retrieved 1 October 2011.
  28. ^ Fiedal, Stuart (2009). "Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction". In Haynes, Gary (ed.). American Megafaunal Extinctions at the End of the Pleistocene. Springer. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9.
  29. ^ Prehistoric Predators (DVD ASIN-B00120TJFE). National Geographic. February 12 2008. {{cite AV media}}: Check date values in: |date= (help)