A bone-cracking, flesh-shredding wolf with massive teeth and a broad head thrived in Alaska until 12,000 years ago, according to a paper published today in Current Biology.
The ancient wolf's enhanced ability to bite likely enabled it to compete with other formidable Alaskan predators at the time, such as saber-tooth cats, short-faced bears and lions. From the exterior it looked like modern gray wolves, but not quite.
"The difference would be subtle - a somewhat broader head and shorter snout - but clearly recognizable as Canis lupus," co-author Blaire Van Valkenburgh, a professor of ecology and evolutionary biology at the University of California, Los Angeles, told Discovery News.
The biggest difference was in its genes.
The scientists analyzed DNA from remains of 20 of the now extinct wolves. Then they compared these gene sequences to those of 436 modern wolves from around the world.
The prehistoric Alaskan wolf was found to be more closely related to ancient Czech, Siberian Russian, and Ukrainian wolves than it was to any living wolves from the Old and New Worlds.
"This confirms previously held ideas that gray wolves invaded North America from the Old World via the Beringian land bridge (that once joined Alaska and Siberia) and traveled south of the ice sheets prior to the last glacial maximum 18,000 years ago," Van Valkenburgh said.
The researchers also compared tooth wear in the ancient wolf with that of 313 modern, wild wolves from four North American subspecies. The early Alaskan wolf tooth wear shows the animal frequently gnawed large bones with its incisors and then cracked the bones with its cheek teeth, somewhat similar to how spotted hyenas eat today.
Van Valkenburgh explained that wolves, and other large carnivores, "tend to consume more bone when prey is more difficult to acquire." They also will "eat more rapidly, which increases the risk of tooth fracture, when competition among carnivore species is high," since these other predators could come along and steal the food.
Bone collagen samples collected from the Pleistocene Alaskan wolves suggest the toothy animal's prey included horses, caribou, bison, yak, woodland muskoxen and mammoths.
Because the prehistoric gray wolf was more specialized for feeding on such large prey, its numbers dwindled to nothing when the Alaskan megafauna disappeared due to hunting and/or climate change, the researchers believe.
R. Dale Guthrie, professor emeritus at the Institute of Arctic Biology at the University of Alaska in Fairbanks, told Discovery News that he was surprised to hear about the prehistoric wolf from his home state.
Guthrie said, "It's very interesting and brings to mind the dire wolf," another extinct wolf that coexisted with gray wolves in North America for around 100,000 years. The newly identified ancient Alaskan wolf, however, appears to have been a different species.
Van Valkenburgh and her team worry the prehistoric Alaskan gray wolf's extinction could foreshadow the fate of other specialized carnivores.
She said, "In the present day, specialized subspecies or species, such as the tundra wolf, could be especially vulnerable to the effects of global warming."
In the future, the researchers plan to conduct further DNA, skull and tooth studies on prehistoric and modern wolves to better determine their similarities, physiological variations and unique feeding adaptations.