Natural Trap
Cave in north-central Wyoming is 85 feet deep and almost impossible to
see until you're standing right next to it. Over tens of thousands of
years, many, many animals — including now-extinct mammoths, short-faced
bears, American lions and American cheetahs — shared the misfortune of
not noticing the 15-foot-wide opening until they were plunging to their
deaths.
Now, the U.S. Bureau
of Land Management is preparing to reopen a metal grate over the opening
to offer scientists what may be their best look yet at the variety of
critters that roamed the foothills of the Bighorn Mountains during the
planet's last glacial period around 25,000 years ago.
Des
Moines University paleontologist Julie Meachen said she has been
getting ready to lead the international team of a dozen researchers and
assistants by hitting the climbing gym.
"I'm pretty terrified," Meachen admitted Wednesday.
She
hasn't done any real climbing before, she said, and the only way in is
to rappel down. The only way out is an eight-story, single-rope climb
all the way back up.
The cave
is perpetually cold and clammy, with temperatures in the mid-40s and
humidity around 98 percent. Even Bureau of Land Management regional
paleontologist Brent Breithaupt, who isn't one to get the willies from
lots of animal bones, describes it as a tad creepy.
"One can only hope that, as
a researcher, you're able to leave," said Breithaupt, who visited the
cave as a college student the last time it was open to scientists. "It's
an imposing hole in the ground. But one that actually has very
important scientific value."
Some mammal remains from the cave could be over 100,000 years old, Breithaupt said.
The
remote site is exceptionally well preserved. It's far too challenging
and dangerous to have been trammeled in by casual spelunkers. The Bureau
of Land Management installed the grate to keep people and animals out
in the 1970s.
A mound of dirt
and rock containing layer upon layer of animal bones rises from the
floor of the 120-foot-wide, bell-shaped chamber. Meachen hopes the
remains are sufficiently preserved in the cold, sheltered environment to
contain snippets of genetic information.
Alan
Cooper with the Australian Centre for Ancient DNA at the University of
Adelaide will attempt to retrieve fragments of mitochondrial DNA from
the bones, Meachen said.
Such
analysis wasn't possible the last time scientists dug in the cave and
could shed light on how the animals were related to their modern
counterparts and each other.
"It's
so cold all year long, that it has got just the perfect conditions for
preserving DNA, in multiple species, in large numbers of individuals,"
Meachen said. "Which is not really found anywhere except Siberia and the
Arctic."
Starting Monday,
scientists plan to re-explore the cavern, dig and extract as many
fossils over a two-week period as possible. The researchers will dig by
lights powered by a generator at the surface.
A National Science Foundation grant will enable additional excavations in 2015 and 2016.
One
goal is to learn more about the Pleistocene extinction, which wiped out
dozens of species. Proposed causes include climate change and hunting
by humans, who are thought to have arrived in northern North America
sometime after 17,000 years ago.
The
scrubby, rocky country surrounding the cave probably looks much like it
did back then, though the climate may have been cooler and wetter,
Meachen said.
The scientists
will camp out nearby and plan to make the arduous climb into and out of
the cave no more than once a day. Ropes will haul bones up top in boxes,
Meachen said.
"I don't think it's necessarily going to be easy," she said. "But I think we're going to be pretty well prepared."
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