"North American lions , cheetahs and short-faced bears: Those are just a few fearsome critters from 25,000 years ago paleontologists already might have found in their first excavation of a bizarre northern Wyoming cave in 30 years." Source: CBS News (2014).
 According to National Geographic (2010), the "American lion" may not be a lion at all, but a kind of jaguar.
"The only way in or out of Natural Trap Cave is a 15-foot-wide hole in the ground that's almost impossible to see until you're next to it. Over tens of thousands of years, several thousand insufficiently wary animals plummeted more than 80 feet into the chilly, dim, cathedral-like cavern." (CBS News)
Excavations in the cave were carried out back in the 1970s and 1980s, followed by a period of inactivity until 2014. A later expedition (2016) discovered a new type of wolf in the cave: "A wolf with stronger jaws, an appetite for megafauna, and one that paleontologists never expected to find so far south. according to Scientific American (2016). Until this discovery, "the wolves of the Wyoming boneyard were categorized as either gray wolves or dire wolves."
In 2015, the Billings Gazette reported that "In addition to the American lion, the team has discovered bones from camels, the American cheetah and a tiny fragment of a mammoth’s tooth in the past two years. They also found remains from wolves, weasels, foxes, bighorn sheep, pronghorn and many horses."
Next video report is from 2014 and features a typically stupid intro.
"Scientists doubt that humans played a role in forcing wildlife into Natural Trap Cave. The bell-shaped cave, nearly impossible for humans to safely enter and exit, never yielded any evidence of human occupations. Scientists believe instead that the cave was located within a major wildlife migratory corridor. The cave is closed to protect paleontological resources." Source: National Park Service.
Comment: I'm probably suffering from a bad case of romantic primitivism, but I'd love to be able to go back in time to prehistoric North America when it was still a wilderness populated by jaguars, mammoths, dire wolves and short-faced bears. Of course, if I accidentally stumbled into a time portal and found myself stranded in Wyoming 20,000 years ago, I'd probably starve to death in a couple of weeks or end up getting eaten myself, but it might be worth it just to catch a glimpse of the country before it was overrun by strip-malls and thumb-typing Ipod zombies.