DNA analysis reveals extinct type of wolf.

Many species of large mammals went extinct when the last ice age ended about 12,000 years ago. But Canis lupus, the gray wolf, survived that wrenching period unscathed--or so scientists thought. New genetic analyses of the remains of gray wolves found in Alaska indicate, however, that a distinct subspecies of C. lupus disappeared at that time, possibly because of its dietary habits.

Blaire Van Valkenburgh of the University of California, Los Angeles and her colleagues conducted a genetic study of living gray wolves and also samples of mitochondrial DNA recovered from wolf bones found in Alaskan permafrost. The remains of those 21 animals ranged in age from 12,600 years to at least 47,000 years.

The team's analyses revealed 15 combinations of genetic variations in the Alaskan wolves that didn't match any of those in 126 modern gray wolves. "This was surprising, so then we looked at the bones," says Van Valkenburgh. They found that the ancient gray wolves had broader snouts, larger teeth, and deeper jaws than their living cousins.

Overall, the findings suggest that the ancient gray wolves belonged to a subspecies adapted to consume bones and carcasses more thoroughly than living wolves do.

The gray wolf subspecies might not have survived the end of the ice age because it depended on a steady supply of large carcasses, says Van Valkenburgh. As the populations of mammoths, mastodons, and other large mammals dwindled, the wolves' food supply would have disappeared, she notes.--S.P.