A hole in flat ground that collected Ice Age animals for tens of thousands of years
Natural Trap Cave is a bell-shaped pit in the Madison Limestone of the Bighorn Mountains, northeast of Lovell in northern Wyoming, at about 4,560 feet. Its mouth is only 12 by 15 feet, and as the National Park Service puts it, the hole is virtually impossible to see until it is directly underfoot. Below it the shaft drops some 80 to 85 feet into a chamber around 120 feet across. Animals walking the ground above kept falling in and could not climb out, and over tens of thousands of years their bones piled up more than 10 metres deep, one of the richest records of the North American Late Pleistocene.
Lawrence Loendorf of the University of Missouri began collecting there in 1970 and excavating in 1971, and in 1972 Carol Jo Rushin of the University of Montana dug a pit 10 feet square at the foot of the entrance drop, recovering bones of 20 kinds of mammals and five of birds, a dire wolf, an ancient horse and a mammoth among them. The Universities of Missouri and Kansas worked through the 1970s, and more than 30,000 specimens have come out, mostly of extinct animals: short-faced bears, American lions, camels, bison, bighorn sheep, wolverines and collared lemmings, and the American cheetah in unusual numbers. The layers lie in order, and they show the region's climate turning from glacial to today's high desert within about 500 years.
People were rarely part of it. A red jasper knife was found below the entrance drop and a possible atlatl shaft in a rat's nest, but the Park Service notes the cave never yielded evidence of human occupation and was nearly impossible to enter and leave safely. Scientists think it sat in a major wildlife migration corridor.
For almost thirty years the Bureau of Land Management kept the entrance under a safety grille. In July and August 2014 a team led by the paleontologist Julie Meachen of Des Moines University went back in for the first of three annual digs, bringing out 200 large bones and countless microfossils. The cave stays below 10 °C at 98 percent humidity, good conditions for ancient DNA, and samples went to the Australian Centre for Ancient DNA to look into why the megafauna died out. A pack rat that fell in during the dig was left where it lay to study decay. The cave remains closed to protect its fossils.
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