Feb 16, 2016

Cave outside Lovell holds remains of many extinct species

“Let’s jump into the cave,” said Gretchen Hurley, geologist with the Bureau of Land Management Cody field office.

Hurley received a hardy laugh from the packed house at Buffalo Bill Center of the West’s Draper Museum of Natural History during the December Lunchtime Expedition.

“Not literally,” Hurley clarified.

BLM geologist Lisa Marks holds a replica of a short-faced bear skull. Short-faced bears roamed the state 1.8 million to 11,000 years ago and dwarfed today's biggest grizzlies, weighing up to 3,500 pounds. Cody News Co. photos by Gib Mathers
She was referring to the Natural Trap Cave in the Big Horn Mountains northeast of Lovell. There, wildlife as far back as 100,000 years ago unwittingly fell to their death, thereby creating a record of the types of Ice Age creatures — some, long extinct — that lived and died in Wyoming.

(For reference, many scientists believe the first people arrived on this continent around 11,000 years ago.)

The cave, with a 15-foot wide opening is 90 feet deep with a 90-foot wide chamber. It formed about 12.5 million years ago and continues to grow as water slowly decays the cave’s ceiling.

“It’s a perfect natural trap,” Hurley said.

Why would the animals fall into the cave to their certain death?

It is possible that a prey animal, such as a pronghorn being chased by an American cheetah (remains of both have been found in the cave) would not see the cave entrance while sprinting over the landscape until it was too late, Hurley said.

Other animals, such as wolves, might have been drawn to the scent of carcasses in the cave, sniffed around the opening and accidentally slipped and fell in.

Assorted varieties of horses have been found in the cave sediments, as well as mammoth, bighorn sheep, the American pronghorn, extinct bison and dire and gray wolves, Hurley said.

No saber tooth tigers have been found, but they were native to ancient Wyoming, Hurley said. Two other species missing are elk and deer.

Additionally, no human remains have been discovered in the cave thus far. However, a pack rat's stash did reveal part of an atlatl shaft, Hurley said. (An atlatl allowed a spear bearer to throw with greater accuracy and velocity.) No date has been provided, but the shaft is probably less than 1,000 years old.

UNEARTHING RESUMES
Lawrence Loendorf was the first to officially explore the cave and its long-deceased occupants from 1970-76. From 1974-85, the universities of Missouri and of Kansas conducted paleontological excavations in the cave. Between 1970-1985, about 40,000 bones were collected by the two universities, Hurley said. “And then the cave was quiet about 30 years.”

Gretchen Hurley
Exploration of the cave was renewed in 2014. Dr. Julie Meachen, Des Moines University, Des Moines, Iowa, and Dr. Alan Cooper, Australian Center for Ancient DNA, University of Adelaide, Adelaide, South Australia, are now leading the project, Hurley said.

During the 2014-15 seasons, species of now-extinct horses were found in the sediments of the soft cave floor, which require little more than a trowel and brush to unearth, Hurley said. Most of an American cheetah's skull was also found last year.

Bighorn sheep, camels, dire and gray wolves and a short-faced bear’s remains have been unearthed. These bears, about twice the size of a grizzly bear, had longer legs and were taller and faster than today’s grizzly bear, Hurley said. An illustration shows the short-face bear as tall as a man while on all fours.

A dire wolf skull replica on the stage made a nearby coyote skull look like the skull of a squirrel by comparison.

Bones of an American lion have also been found. It was similar to lions in present day Africa, Hurley said. It came from Beringia, across the now submerged Bering land bridge, which was intact during the Pleistocene epoch (from 1.64 million to about 10,000 years ago).

It is believed by many scientists that America’s first humans crossed the miles-wide bridge, along with animal and plant species.

Portions of a Columbian mammoth — extinct 11,000 years — were discovered in the 1980s.

Sediments in the cave may be as old as 600,000 years, which corresponds to the last time the Yellowstone volcanic center erupted, Hurley said. 

The scientists will begin publishing papers about their findings in 2016.

Replicas of ancient animal skulls
“This is an international project taking place on your public lands,” Hurley said. “It’s world class.”

Scientists are examining isotopes and DNA from the cave’s fossils in an effort to determine what caused species’ extinctions about 11,000 years ago, Hurley said.

They are also sampling pollen, which allows scientists to determine the vegetation types in the area during the Pleistocene epoch, Hurley said.

The Natural Trap Cave formed in beds of compressed limestone that were squeezed structurally in a monocline (a bend in rock strata), Hurley said. Water dissolves limestone, forming carbonic acid, which further dissolves the limestone, forming caverns.

The bones in cave have been very well preserved, in “a natural refrigerator for all these years,” Hurley said.

Perhaps the spirits of the wildlife that came to a sudden and violent end still haunt the ancient sepulcher.

“You go down there and it feels like you stepped back into the Pleistocene (epoch),” Hurley said. “This kind of project comes along a once in a lifetime, and it’s a real privilege to work on this.”

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