Scientists unearthed a mass grave filled with prehistoric animals after excavating an unexplored cave in the foothills of Wyoming’s Bighorn Mountains.

Natural Trap Cave, first discovered in the 1970s, consists of a 15-foot wide opening followed by an 85-foot drop down into a sinkhole; animals that espy the crevice and venture through it ultimately have little chance of survival. Though an unfortunate demise for the beasts, the cold, damp conditions within the pitfall preserved the bodies quite well– an unexpected stroke of fortune for the scientists.

“Some bones still have collagen with intact DNA for genetic testing and some fossils are fragments crushed by rocks. But we take it for what it is when we find it,” said Julie Meachen, Des Moines University paleontologist and leader of the international team of scientists, in an interview with Reuters.

The dig began last month, uncovering around 200 bones of large animals that ruled North America during the Ice Age (12,000 to 23,000 years ago) as well as numerous microfossils of vertebrates such as birds, lizards and snakes.

“We found evidence of bison, a bit of gray wolf and quite a lot of cheetah and horse,” said Meachen.

While working on the dig, Meachen and her team were treated to a firsthand view of the cave’s deadly processes. Two rodents, a pack rat and a deer mouse, tumbled into the abyss during the excavation. The deer mouse survived the fall, was rescued and transported out of the cavern via a bucket-and-pulley system before being nursed back to health by the team. The pack rat succumbed to injury, and was left in the cave so that the team can study decomposition rates of the cave during two more scheduled trips in the upcoming years.

The fossils will provide scientists with a better understanding of the biodiversity of animal species, insights into their diets, as well as provide data about the climate conditions of the Ice Age in North America. Meachen hopes that such information can help reveal how climate change and the extinction events at the end of the Ice Age affected the form, structure, and functions of species living today.