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Pam Groves pointing to steppe bison head in river bank
Pam points to the upside-down skull still buried in river bank; this scene is what they first spotted that alerted them to the skeleton.
Intact 40,000-year-old skeleton of a steppe bison offers new insights for Alaska researchers

Bison Bob, as University of Alaska Fairbanks researchers named the 12-year-old male steppe bison, was probably having a sip of water or contemplating crossing a river on Alaska’s North Slope about 40,000 years ago when his heavy hoofs began sinking into the river bank. Quicksand slowly entombed the bison, where he lay undiscovered until the summer of 2012.  That’s when Pam Groves and Dan Mann discovered his skull protruding from the thawing river bank in the BLM-managed National Petroleum Reserve in Alaska.

Groves, a BLM seasonal employee, and Mann, a BLM volunteer at the time (both have been BLM summer employees for many of the past 15 years), were collaborating with now-retired BLM archaeologist Mike Kunz to search for skeletons or mummies of ice-age mammals such as horses, mammoths, or American lions, when they came across Bison Bob’s almost completely intact skeleton. 
Steppe bison (Bison priscus) lived during the Pleistocene Era, from about 2 million years ago to about 10,000 years ago.  The bison were common in Europe, central Asia, North America, and Beringia (a region in the north Pacific that included the ancient Bering land bridge, roughly 1,000 miles wide north to south at its greatest extent, that connected Asia with North America at various times during the Pleistocene ice ages).  The bison shared the grassy landscape in Alaska with mammoth, musk oxen, horses, caribou, lions, wolves and two species of bears. Although other steppe bison, notably Blue Babe, were discovered in Alaska, Bison Bob is an important find because his skeleton is so complete.  The spread of his horns is 43 inches, which far exceeds the record of 27 inches on a skull of a Boone and Crockett modern bison. 

Pam washing back bone with water
Groves hauled heavy buckets of water up the bluff to thaw out the sediments holding the bones.  Here, she exposes some of the backbone as the sediments melt and wash away.
Pam Groves pointing to steppe bison head in river bank
Dan Mann holds Bison Bob’s skull just after it was removed from the river’s bank.

Careful excavation of Bison Bob’s skull took about four hours.  After another three days of digging out bones still held together by ligaments and tufts of the steppe bison’s brown fur, Groves and Mann found that the only bone missing from the skeleton was the left shoulder blade. 
exposed leg bonepam holding back bonesDan holds bison front leg
The end of a leg bone and lots of bison-hair protrude from frozen bluff sediments.Pam holds a back bone section they retrieved from frozen sediments; the vertebrae are still attached to each other with connective tissue.Dan holds one of Bison Bob’s front legs; the humerus and radius are still attached to each other.

After freeing the bison, a helicopter transported him to a North Slope BLM camp, where they placed Bison Bob in a predator-proof case and flew him to Fairbanks.  This is where he now resides in a freezer with tundra-like conditions, awaiting further examination.  His hair, teeth, horn sheaths, and hooves will be analyzed for isotopes that may reveal what he ate, how his diet changed, and even whether he migrated into areas like Alaska’s Brooks Mountain Range during the winter.  BLM-Alaska has permitted the university researchers’ bone work for 15 years and has provided all of the logistical support, including helicopter, other air travel, and accommodations at the Inigok and Ivotuk base camps. Bison Bob will eventually be on display at the University of Alaska’s Museum of the North in Fairbanks, and Groves and Mann hope to make a replica of the skeleton for the BLM to also put on display.

All photos courtesy of BLM-Alaska

Last updated: 07-22-2016