Ice Age fossils found in 25,000-year-old sinkhole

By Casey Frye, CCNN Writer

Wyoming cave
Scientists make the 85-foot descent into the Natural Trap Cave with ropes and hooks.

When underground rocks and dirt get worn away, they sometimes collapse into a big sinkhole that leaves a gaping pit of blackness in the Earth’s surface. About 25,000 years ago, a mega sinkhole opened up in the state of Wyoming, and all kinds of prehistoric mammals like the North American lion and American cheetah fell into it over time.

Called the Natural Trap Cave, this boneyard of long extinct creatures had gone unexplored for over 30 years, but it’s now become a treasure trove for paleontologists (fossil scientists) who are finding hundreds upon hundreds of well-preserved skeletal remains!

Located at the base of the Bighorn Mountains in northern Wyoming, the Natural Trap Cave contains fossils dating back to the Ice Age, which took place about 110,000 to 12,000 years ago. Earth has gone through a few of these glacial periods, when there’s a pattern of global cooling that results in the presence of massive ice sheets in the northern and southern regions of our planet.

How did the animal bones last so long down there? Well, because of the cool and dark conditions of this sinkhole, it acted kind of like a refrigerator, keeping the remains of those old critters nice and fresh.

In order to reach the bottom, Australian and American researchers climbed down the 85-foot drop with ropes and hooks. After rummaging around in the dirt, they’ve uncovered fossils of short-faced bears, collared lemmings, mammoths, and even camels! That’s just the beginning, though, as scientists believe they’ll find thousands more bones… some of which might be up to 100,000 years old.

Images courtesy of L. Weyrich and The University of Adelaide.