The ancient gray wolves that once roamed the icy expanses of Alaska represented a specialized form that apparently died out along with other big animals at the end of the Pleistocene, many thousands of years ago, researchers report online on June 21st in the journal Current Biology, a publication of Cell Press. The extinct Alaskan wolves had robust bodies, strong jaws, and massive canine teeth for killing prey larger than themselves and regularly consuming large bones, according to the researchers.
“Our results are surprising as the unique attributes of Alaskan Pleistocene wolves had not been previously recognized and show that wolves suffered an extinction at the end of the Pleistocene,” said Blaire Van Valkenburgh of the University of California, Los Angeles. “If not for their persistence in the Old World, we might not have wolves in North America today. Regardless, the living gray wolf differs dramatically from that which roamed Alaska just 12,000 years ago.”
The gray wolf is one of the few large predators that survived the mass extinction of the late Pleistocene. Nevertheless, wolves disappeared from northern North America at that time.
To further explore the identity of Alaska’s ancient wolves in the new study, the researchers collected skeletal remains of the animals from Pleistocene permafrost deposits of eastern Beringia and examined their chemical composition and genetic makeup.
Remarkably, they discovered that the late-Pleistocene wolves were distinct from existing wolves, both genetically and in terms of their physical characteristics. None of the ancient wolves were a genetic match for any modern wolves, they report. Moreover, the animals’ skull shape and tooth wear, as well as a chemical analysis of their bones, all suggest that eastern Beringian wolves were specialized hunters and scavengers of extinct megafauna.
“The ancient wolves had relatively more massive teeth and broader skulls with shorter snouts, enhancing their ability to produce strong bites,” Van Valkenburgh said. “In addition, the studies of their tooth wear and fracture rate showed high levels of both, consistent with regular and frequent bone-cracking and -crunching behavior.”
Those characteristics probably came in handy in ancient Alaska, where the wolves faced stiff competition for food from some very formidable competitors, she added, including lions, short-faced bears, and saber-tooth cats. During periods of intense competition among predators, modern-day wolves will also consume carcasses more fully, ingesting more bone and eating faster, which increases the risk of tooth fracture.
The long-ago demise of this specialized wolf form may portend things to come for specialized groups of existing predators, Van Valkenburgh said. For example, a unique type of nomadic North American gray wolf was recently discovered. Their packs migrate across the North American tundra along with caribou and keep their numbers in check. In contrast, all other wolves are territorial and non-migratory. “Global warming threatens to eliminate the tundra and it is likely that this will mean the extinction of this important predator,” she said.
The researchers include Jennifer A. Leonard of the University of California, Los Angeles, CA, National Museum of Natural History, Smithsonian Institution, Washington, DC, and Uppsala University, Uppsala, Sweden; Carles Vilà of Uppsala University, Uppsala, Sweden; Kena Fox-Dobbs and Paul L. Koch of University of California, Santa Cruz, CA; Robert K.Wayne and Blaire Van Valkenburgh of University of California, Los Angeles, CA.
This work was funded by the National Science Foundation OPP 9817937 (RKW, BVV), OPP 0352634 (RKW, JAL, PLK), and the Swedish Research Council (JAL, CV).
Leonard et al.: “Megafaunal extinctions and the disappearance of a specialized wolf ecomorph.” Publishing in Current Biology 17, 1–5, July 3, 2007. DOI 10.1016/j.cub.2007.05.072. www.current-biology.com
Journal
Current Biology