Observations of the Acetabulum and Proximal Femur of the Dire Wolf (Canis dirus, Leidy 1854)

Inferences concerning the lives of extinct animals are difficult to obtain from the fossil record. Here we present a novel approach to the study of extinct carnivores, using a comparison between fossil records ( n =3324) found in Late Pleistocene tar seeps at Rancho La Brea in North America and counts ( n =4491) from playback experiments used to estimate carnivore abundance in Africa. Playbacks and tar seep deposits represent competitive, potentially dangerous encounters where multiple predators are lured by dying herbivores. Consequently, in both records predatory mammals and birds far outnumber herbivores. In playbacks, two large social species, lions, Panthera leo , and spotted hyenas, Crocuta crocuta , actively moved towards the sounds of distressed prey and made up 84 per cent of individuals attending. Small social species (jackals) were next most common and solitary species of all sizes were rare. In the La Brea record, two species dominated, the presumably social dire wolf Canis dirus (51%), and the sabretooth cat Smilodon fatalis (33%). As in the playbacks, a smaller social canid, the coyote Canis latrans , was third most common (8%), and known solitary species were rare (<4%). The predominance of Smilodon and other striking similarities between playbacks and the fossil record support the conclusion that Smilodon was social.

Download Full-text

Hypercarnivorous teeth and healed injuries to Canis chihliensis from Early Pleistocene Nihewan beds, China, support social hunting for ancestral wolves

PeerJ ◽

10.7717/peerj.9858 ◽

2020 ◽

Vol 8 ◽

pp. e9858

Author(s):

Haowen Tong ◽

Xi Chen ◽

Bei Zhang ◽

Bruce Rothschild ◽

Stuart White ◽

...

Keyword(s):

Large Body ◽

Family Care ◽

Northern China ◽

Early Pleistocene ◽

History Of ◽

Behavioral Evidence ◽

Displaced Fracture ◽

Canis Dirus ◽

Dire Wolf ◽

Rancho La Brea

Collaborative hunting by complex social groups is a hallmark of large dogs (Mammalia: Carnivora: Canidae), whose teeth also tend to be hypercarnivorous, specialized toward increased cutting edges for meat consumption and robust p4-m1 complex for cracking bone. The deep history of canid pack hunting is, however, obscure because behavioral evidence is rarely preserved in fossils. Dated to the Early Pleistocene (>1.2 Ma), Canis chihliensis from the Nihewan Basin of northern China is one of the earliest canines to feature a large body size and hypercarnivorous dentition. We present the first known record of dental infection in C. chihliensis, likely inflicted by processing hard food, such as bone. Another individual also suffered a displaced fracture of its tibia and, despite such an incapacitating injury, survived the trauma to heal. The long period required for healing the compound fracture is consistent with social hunting and family care (food-sharing) although alternative explanations exist. Comparison with abundant paleopathological records of the putatively pack-hunting Late Pleistocene dire wolf, Canis dirus, at the Rancho La Brea asphalt seeps in southern California, U.S.A., suggests similarity in feeding behavior and sociality between Chinese and American Canis across space and time. Pack hunting in Canis may be traced back to the Early Pleistocene, well before the appearance of modern wolves, but additional evidence is needed for confirmation.

Download Full-text

The Dire Consequences of Specializing on Large Herbivores

USURJ University of Saskatchewan Undergraduate Research Journal ◽

10.32396/usurj.v5i1.347 ◽

2018 ◽

Vol 5 (1) ◽

Author(s):

Branden T. Neufeld

Keyword(s):

Canis Lupus ◽

Prey Species ◽

Niche Differentiation ◽

Similar Species ◽

Grey Wolf ◽

Large Herbivores ◽

The North ◽

Extinction Event ◽

Canis Dirus ◽

Dire Wolf

Niche differentiation is a way in which similar species avoid competition. Some species do this by specializing in certain prey items. This review aims to determine why the dire wolf (Canis dirus) went extinct while its similar and less abundant relative, the grey wolf (Canis lupus) did not. Both species were present in North America during the Pleistocene, though only one went extinct during the Quaternary extinction event. Physiological differences existed between the two species, mostly due to a greater focus in hypercarnivory for dire wolves. Dire wolves had more robust frame and skull, greater bite strength, and larger carnasials and canines. These differences in dire wolf morphology all help it to handle and kill larger prey species, while the more lithe grey wolf is better adapted to switching to smaller alternative prey. Dire wolves at have been shown to consume mostly large herbivores while grey wolves can survive with lagomorphs as a primary food source. Larger carnivore body size means reduction in locomotor performance, which means that when many mega-herbivores went extinct at the end of the Pleistocene, dire wolves were not as well adapted to switch to smaller prey as grey wolves are. Their naturally larger body mass also means that they needed higher caloric input to maintain their body condition and fecundity. Overall, Canis dirus specialized in larger prey than Canis lupus, so when this prey became extinct, the dire wolf went extinct along with other hypercarnivores such as the North American lion, Smilodon, and short-faced bear.

Download Full-text