As she scraped cold dirt from the remains of an extinct bison, Pam Groves wrinkled her nose at a rotten-egg smell wafting from gristle that still clung to the animal's bones. She lifted her head to scan the horizon, wary of bears that might be attracted to the flesh of a creature that gasped its last breath 40,000 years ago.
In the type of discovery they have dreamed about for years, Groves and Dan Mann, both researchers at the University of Alaska Fairbanks, in summer 2012 found in the thawing bank of a northern river almost the entire skeleton of a steppe bison that died during the last ice age.
In adventurous work sponsored by the Bureau of Land Management, Mann and Groves have been boating down lonely northern rivers for 15 years looking for scattered bones of ice age mammals, always hoping to find a complete skeleton or mummy of a mammoth, horse, or American lion. In mid-June, on a familiar stretch of river that flows northward on Alaska's North Slope, they rounded a river bend and saw the skull of a large bison trapped against a willow shrub.
Groves described the scene: "We were paddling downriver, battling through a nasty squall of hail and wind, thinking about our camping spot about a mile downriver," she said. "When the hail was just breaking up, we saw the upside-down skull with the lower jaw still attached. The teeth were really white. They stood out."
The pair landed their inflatable canoe at the base of the 60-foot bluff. Even before they stepped out in their rubber boots, Groves spotted other bones that told her this wasn't an ordinary site. Though this ever-changing wall had yielded many bones over the years, those were scattered remains of ice-age creatures separated by meandering river action and the crumbling and re-forming of permafrost-cemented bluffs. Mann said their typical discoveries resemble "Pleistocene in a blender." ...