page_title: Dire wolf
section_title: Tooth breakage
hierarchical_section_title: Dire wolf / Adaptation / Behavior / Tooth breakage
caption_attribution_description: English: Canis dirus Leidy, 1858 - fossil dire wolf skull from the Pleistocene of North America. (public display, Sternberg Museum of Natural History, Hays, Kansas, USA) From museum signage: "Dire wolves are closely related to the modern gray wolf. Their fossils have been found in great numbers in the tar pit deposits of California. The wolves were attracted to other animals trapped in the tar, and became trapped themselves. Dire wolves were widespread across North America during the Ice Age. They lived and hunted in packs like their modern cousins." "Extreme Pack Hunting The dire wolf (Canis dirus) evolved in North America, alongside the coyote (Canis latrans), and ranged from Alaska to Florida. The gray wolf (Canis lupus) migrated to North America from Asia some 200,000 years ago and subsequently coexisted with the dire wolf. The dire wolf and gray wolf are very similar in height and length, but the dire wolf was stockier with a broader head and larger teeth, and had shorter sturdier legs. Dire wolves may have hunted in large packs of 30 or more individuals, which is different from modern gray wolves that generally live in smaller packs of 5-10 individuals. Large pack size means dire wolves were mostly hunting large prey, and these large packs made them extremely successful predators during the Pleistocene. An example of their success can be seen in the La Brea tar pits in California where dire wolf skeletons outnumber gray wolf skeletons by nearly 200 to 1. The dire wolf had a diet dominated by bison and horse, but excluding elk, deer, and smaller prey. Soon after the extinction of horses, mammoths, and several bison species, the dire wolf also went extinct. On the other hand, modern gray wolf diet includes a broad range of prey including medium to large mammals such as deer, elk, muskox, carivou, and bison, as well as smaller prey such as hares, badgers, foxes, rodents, and waterfowl. Shortly following the dire wolf extinction, the domestication of gray wolves by humans began. " Classification: Animalia, Chordata, Vertebrata, Mammalia, Carnivora, Canidae See info. at: en.wikipedia.org/wiki/Dire_wolf
context_page_description: The dire wolf is an extinct species of the genus Canis. It is one of the most famous prehistoric carnivores in North America, along with its extinct competitor, the sabre-toothed cat Smilodon fatalis. The dire wolf lived in the Americas during the Late Pleistocene and Early Holocene epochs. The species was named in 1858, four years after the first specimen had been found. Two subspecies are recognized: Canis dirus guildayi and Canis dirus dirus. The dire wolf probably evolved from Armbruster's wolf in North America. The largest collection of its fossils has been obtained from the Rancho La Brea Tar Pits in Los Angeles.
  Dire wolf remains have been found across a broad range of habitats including the plains, grasslands, and some forested mountain areas of North America, and in the arid savannah of South America. The sites range in elevation from sea level to 2,255 meters. Dire wolf fossils have rarely been found north of 42°N latitude; there have been only five unconfirmed reports above this latitude. This range restriction is thought to be due to temperature, prey, or habitat limitations imposed by proximity to the Laurentide and Cordilleran ice sheets that existed at the time.
context_section_description: Tooth breakage is related to a carnivore's behavior. A study of nine modern carnivores found that one in four adults had suffered tooth breakage and that half of these breakages were of the canine teeth. The most breakage occurred in the spotted hyena that consumes all of its prey including the bone; the least breakage occurred in the African wild dog, and the gray wolf ranked in between these two. The eating of bone increases the risk of accidental fracture due to the relatively high, unpredictable stresses that it creates. The most commonly broken teeth are the canines, followed by the premolars, carnassial molars, and incisors. Canines are the teeth most likely to break because of their shape and function, which subjects them to bending stresses that are unpredictable in both direction and magnitude. The risk of tooth fracture is also higher when killing large prey.
  A study of the fossil remains of large carnivores from La Brea pits dated 36,000–10,000 YBP shows tooth breakage rates of 5–17% for the dire wolf, coyote, American lion, and Smilodon, compared to 0.5–2.7% for ten modern predators. These higher fracture rates were across all teeth, but the fracture rates for the canine teeth were the same as in modern carnivores. The dire wolf broke its incisors more often when compared to the modern gray wolf; thus, it has been proposed that the dire wolf used its incisors more closely to the bone when feeding. Dire wolf fossils from Mexico and Peru show a similar pattern of breakage. A 1993 study proposed that the higher frequency of tooth breakage among Pleistocene carnivores compared with living carnivores was not the result of hunting larger game, something that might be assumed from the larger size of the former. When there is low prey availability, the competition between carnivores increases, causing them to eat faster and thus consume more bone, leading to tooth breakage. As their prey became extinct around 10,000 years ago, so did these Pleistocene carnivores, except for the coyote (which is an omnivore).
  A later La Brea pits study compared tooth breakage of dire wolves in two time periods. One pit contained fossil dire wolves dated 15,000 YBP and another dated 13,000 YBP. The results showed that the 15,000 YBP dire wolves had three times more tooth breakage than the 13,000 YBP dire wolves, whose breakage matched those of nine modern carnivores. The study concluded that between 15,000–14,000 YBP prey availability was less or competition was higher for dire wolves, and that by 13,000 YBP, as the prey species moved towards extinction, predator competition had declined and therefore the frequency of tooth breakage in dire wolves had also declined.
  Carnivores include both pack hunters and solitary hunters. The solitary hunter depends on a powerful bite at the canine teeth to subdue their prey, and thus exhibits a strong mandibular symphysis. In contrast, a pack hunter, which delivers many shallower bites, has a comparably weaker mandibular symphysis. Thus, researchers can use the strength of the mandibular symphysis in fossil carnivore specimens to determine what kind of hunter it was – a pack hunter or a solitary hunter – and even how it consumed its prey. The mandibles of canids are buttressed behind the carnassial teeth to enable the animals to crack bones with their post-carnassial teeth (molars M2 and M3). A study found that the mandible buttress profile of the dire wolf was lower than that of the gray wolf and the red wolf, but very similar to the coyote and the African hunting dog. The dorsoventrally weak symphyseal region (in comparison to premolars P3 and P4) of the dire wolf indicates that it delivered shallow bites similar to its modern relatives and was therefore a pack hunter. This suggests that the dire wolf may have processed bone but was not as well adapted for it as was the gray wolf. The fact that the incidence of fracture for the dire wolf reduced in frequency in the late Pleistocene to that of its modern relatives suggests that reduced competition had allowed the dire wolf to return to a feeding be
caption: Dire wolf skull and neck
exif: {"Image ImageWidth": "4000", "Image ImageLength": "3000", "Image BitsPerSample": "[8, 8, 8]", "Image PhotometricInterpretation": "2", "Image Make": "Canon", "Image Model": "Canon PowerShot D10", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 13.0 (Macintosh)", "Image DateTime": "2017:01:14 20:00:12", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "304", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1226", "Thumbnail JPEGInterchangeFormatLength": "5061", "EXIF ExposureTime": "3/10", "EXIF FNumber": "49/10", "EXIF ISOSpeedRatings": "320", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2012:06:13 10:52:04", "EXIF DateTimeDigitized": "2012:06:13 10:52:04", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "7/4", "EXIF ApertureValue": "147/32", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "147/32", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "93/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3119", "EXIF ExifImageLength": "2186", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "4000", "Interoperability RelatedImageLength": "3000", "EXIF InteroperabilityOffset": "1076", "EXIF FocalPlaneXResolution": "4000000/243", "EXIF FocalPlaneYResolution": "1500000/91", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}