Who Ate Whom in Ancient Alaska?
The saber-toothed cats of ancient Alaska had a taste for wooly mammoth. Lions preferred bison. The giant, short-faced bear let other animals kill its food.
A University of Alaska researcher has used the bones of animals that roamed the dry Pleistocene grasslands of Alaska to flesh out the interactions between the creatures.
Paul Matheus, of the Alaska Quaternary Center, is a paleobiologist. Part scientist, part detective, he studies the bones of animals that died many thousands of years ago, then pieces together how they lived. Matheus uses collagen, a component of bones, to determine the favorite foods of such animals as the short-face bear and the scimitar cat, a saber-toothed creature smaller than today’s African lion.
Matheus and his colleagues have separated collagen, a protein, from fossilized bones that came from Alaska’s north slope, the Fairbanks area, and an area near Dawson City in the Yukon. The Bureau of Land Management has aided Matheus’ study by loaning him bones found during investigations of the National Petroleum Reserve on Alaska’s north slope. With the collagen from these and other bones, Matheus is able to measure ratios of nitrogen and carbon isotopes that reveal what Mammoth Steppe creatures were eating.
The Mammoth Steppe was a dry, cold grassland that covered most of Alaska during the ice ages of the Pleistocene, which lasted until about 13,000 years ago. Dale Guthrie, a retired biology professor at UAF, compares the Mammoth Steppe of the ancient northland to short-grass prairies that exist today near Minot, North Dakota, and northern Montana. One major difference is the multitude of animals that populated what is now Alaska. American lions lived here, as did wolves, short-faced bears that weighed 1,500 pounds, saber-toothed cats, bison, horses and mammoths. More familiar mammals, such as caribou, muskox, and wolverines, also roamed the grasslands.
The scimitar cat had upper canine teeth that were curved and serrated like steak knives. Some paleontologists speculate the cats developed the teeth for slicing open large, dead animals; others argue they were used to kill small mammoths. The latter envision the cat rushing in, slicing skin, retreating (when larger mammoths encircled the wounded one), and then returning to feed on the carcass after the young mammoth bled to death. The American lion of the ancient north seemed to prefer bison as its primary meal. In Africa today, lions often hunt zebra, but horses—the closest thing to zebras in Pleistocene Alaska—made up a small portion of lion diets. Matheus thinks this result supports the hypothesis that lions evolved as specialized hunters of large bovids (antelope, cattle and bison).
Bigger and lankier than the largest Kodiak brown bear alive today, short-faced bears would have been an imposing feature of the Mammoth Steppe landscape, but Matheus thinks the giant bear may have been an ineffective predator. Its skeleton wasn’t designed to handle the stress of running fast and making quick cuts. Matheus’ study shows that the short-faced bear ate plant-eating animals of all varieties, which is consistent with a scavenger’s behavior.
The isotope signatures of ancient wolves suggest that wolves ate significant amounts of mammoth, which puzzles Matheus because ancient wolves were smaller than today’s wolves. He thinks wolves scavenged, rather than hunted, mammoth meat.
Matheus will soon share his views on ancient northern animals with other experts at the 3rd International Mammoth Conference, held in Dawson City, Yukon, from May 24th -29th, 2003.
