Wyoming 洞穴 with 化石 secrets to be excavated
CHEYENNE, Wyo. (AP) ― For the first time in three １０年間s, scientists are about to revisit one of North America's most remarkable troves of 古代の 化石s: the bones of tens of thousands of animals piled at least 30 feet 深い at the 底（に届く） of a sinkhole-type 洞穴.
Natural 罠（にかける） 洞穴 in north-central Wyoming is 85 feet 深い and almost impossible to see until you're standing 権利 next to it. Over tens of thousands of years, many, many animals ― 含むing now-extinct mammoths, short-直面するd 耐えるs, American lions and American cheetahs ― 株d the misfortune of not noticing the 15-foot-wide 開始 until they were 急落（する），激減（する）ing to their deaths.
Now, the U.S. Bureau of Land 管理／経営 is 準備するing to 再開する a metal grate over the 開始 to 申し込む／申し出 scientists what may be their best look yet at the variety of critters that roamed the 山のふもとの丘s of the Bighorn Mountains during the 惑星's last glacial period around 25,000 years ago.
In an image 供給するd by the Bureau of Land 管理／経営, date not known, Bureau of Land 管理／経営 洞穴 specialist Bryan McKenzie rappels into Natural 罠（にかける） 洞穴 in north-central Wyoming during a cleanup 探検隊／遠征隊. The 洞穴 持つ／拘留するs the remains of tens of thousands of a nimals, 含むing many now-extinct 種類, from the late Pleistocene period tens of thousands of years ago. Starting July 28, 2014, scientists 計画（する） to 投機・賭ける 支援する into the 洞穴 and 再開する digging for the first time in more than 30 years. (AP Photo/Bureau of Land 管理／経営)
Des Moines University paleontologist Julie Meachen said she has been getting ready to lead the international team of a dozen 研究員s and assistants by hitting the climbing gym.
"I'm pretty terrified," Meachen 認める Wednesday.
She hasn't done any real climbing before, she said, and the only way in is to rappel 負かす／撃墜する. The only way out is an eight-story, 選び出す／独身-rope climb all the way 支援する up.
The 洞穴 is perpetually 冷淡な and clammy, with 気温s in the 中央の-40s and 湿度 around 98 パーセント. Even Bureau of Land 管理／経営 地域の paleontologist Brent Breithaupt, who isn't one to get the willies from lots of animal bones, 述べるs it as a tad creepy.
"One can only hope that, as a 研究員, you're able to leave," said Breithaupt, who visited the 洞穴 as a college student the last time it was open to scientists. "It's an 課すing 穴を開ける in the ground. But one that 現実に has very important 科学の value."
Some 哺乳動物 remains from the 洞穴 could be over 100,000 years old, Breithaupt said.
The remote 場所／位置 is exceptionally 井戸／弁護士席 保存するd. It's far too challenging and dangerous to have been trammeled in by casual spelunkers. The Bureau of Land 管理／経営 任命する／導入するd the grate to keep people and animals out in the 1970s.
A 塚 of dirt and 激しく揺する 含む／封じ込めるing 層 upon 層 of animal bones rises from the 床に打ち倒す of the 120-foot-wide, bell-形態／調整d 議会. Meachen hopes the remains are sufficien tly 保存するd in the 冷淡な, 避難所d 環境 to 含む／封じ込める snippets of genetic （警察などへの）密告，告訴（状）.
Alan Cooper with the Australian Centre for 古代の デオキシリボ核酸 at the University of Adelaide will 試みる／企てる to retrieve fragments of mitochondrial デオキシリボ核酸 from the bones, Meachen said.
Such 分析 wasn't possible the last time scientists dug in the 洞穴 and could shed light on how the animals were 関係のある to their modern 相当するものs and each other.
"It's so 冷淡な all year long, that it has got just the perfect 条件s for 保存するing デオキシリボ核酸, in 多重の 種類, in large numbers of individuals," Meachen said. "Which is not really 設立する anywhere except Siberia and the 北極の."
Starting Monday, scientists 計画（する） to re-調査する the cavern, dig and 抽出する as many 化石s over a two-week period as possible. The 研究員s will dig by lights 力／強力にするd by a 発生させる人（物） at the surface.
A 国家の Science 創立／基礎 認める will enable 付加 穴掘りs in 2015 and 2016.
One goal is to learn more about the Pleistocene 絶滅, which wiped out dozens of 種類. 提案するd 原因（となる）s 含む 気候 change and 追跡（する）ing by humans, who are thought to have arrived in northern North America いつか after 17,000 years ago.
The scrubby, rocky country surrounding the 洞穴 probably looks much like it did 支援する then, though the 気候 may have been cooler and wetter, Meachen said.
The scientists will （軍の）野営地，陣営 out nearby and 計画（する） to make the arduous climb into and out of the 洞穴 no more than once a day. Ropes will 運ぶ／漁獲高 bones up 最高の，を越す in boxes, Meachen said.
"I don't think it's やむを得ず going to be 平易な," she said. "But I think we're going to be pretty 井戸／弁護士席 用意が出来ている."
In an image 供給するd by the Bureau of Land 管理／経営, date not known, Bureau of Land 管理／経営 洞穴 specialist Bryan McKenzie rappels into Natural 罠（にかける） 洞穴 in north-central Wyoming during a cleanup 探検隊／遠征隊. The 洞穴 持つ／拘留するs the remains of tens of thousands of animals, 含むing many now-extinct 種類, from the late Pleistocene period tens of thousands of years ago. Starting July 28, 2014, scientists 計画（する） to 投機・賭ける 支援する into the 洞穴 and 再開する digging for the first time in more than 30 years. (AP Photo/Bureau of Land 管理／経営)
