Bone-Crushing Wolves Roamed Alaska During Ice Age
for National Geographic News
|June 21, 2007|
Gray wolves that roamed Alaska during the last ice age were built to tackle prey much larger than themselves and devour them completely—bones and all—a new study says.
The ancient wolves had short snouts, strong jaws, and massive canine teeth unlike those on any wolves today.
But these Alaskan wolves died out along with mastodons, saber-toothed cats, and other big animals at the end of the Pleistocene epoch, about 10,000 years ago.
The finding is based on an analysis of skull and tooth bones collected decades ago from the permafrost and stored today at museums in the U.S. and Canada.
The wolves were specially adapted to a highly competitive life on the vast, icy Alaskan expanses, according to the study, which examined bone shape and DNA and chemical signatures in the bones.
"Certainly, competition would favor those adaptations," said study co-author Blaire Van Valkenburgh, a professor of ecology and evolutionary biology at the University of California, Los Angeles.
She noted that the ancient wolves in Alaska didn't have to compete with larger relatives called dire wolves. This allowed the Alaskan gray wolves to fill a niche unavailable to gray wolf populations farther south.
"If there are advantages, as there generally are, to being stronger, then evolution will proceed in that direction," she said.
The study was published online today in the journal Current Biology.
The ancient Alaskan wolves' short snouts, broad skulls, and large teeth "indicate a specialization for big bite forces," Van Valkenburgh added.
Many of the teeth were also worn down and fractured. This shows that the wolves were eating a lot of bones for nutrition as the animals competed for access to limited prey.
Ice Age carnivores from a cave in Mexico and tar pits in Peru and California also have high rates of tooth wear and fracture, according to the researchers.
"If you killed something, you were likely to have someone come and try to steal it, and so it would behoove you to eat very rapidly and to consume as much of what you killed as possible," Van Valkenburgh said.
Chemical signatures in the wolf bones suggested the animals ate a varied diet of mammoth, musk ox, bison, and horse.
The ancient Alaskan wolves were also genetically distinct from any wolves living today, the authors add.
"If this animal were alive today, it would be classified as a distinct subspecies," Van Valkenburgh said.
Kathleen Lyons is a biologist at Old Dominion University in Norfolk, Virginia, who studies late Pleistocene mammals to understand how current climate change might affect species diversity.
She was not involved in the new research. But she said it is a "great example of how using different lines of evidence can give you a full picture of an extinct animal."
Ice Age Extinction
Like much of their prey and contemporary carnivores, the specialized Alaskan wolves disappeared at the end of the Ice Age.
Scientists have long debated the causes of these extinctions. Some studies link the demise to overhunting by humans. Other studies suggest a warming climate doomed the animals.
And a recent controversial theory says a comet or meteor exploded over northern North America and triggered the die-off.
Study co-author Van Valkenburgh said her study fails to shed light on the cause of the extinction. But "it's most likely that the carnivores went extinct as a result of their prey going extinct."
This kind of effect on Ice Age carnivores highlights a problem for conservation efforts that target a single predator species as the Earth warms and alters landscapes, noted Lyons, of Old Dominion University.
"If you don't preserve the species' habitat and the species' prey species," she said, "then your efforts to try and preserve a species are going to be problematic at best."
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