The Clovis people were a prehistoric Native American culture that existed roughly 13,200 to 12,900 years ago who suddenly died out at the end of the last Ice Age, along with 35 iconic species of animals with little or no explanation as to why – until now.

A team of three archaeologists at the University of South Carolina recently published a study which looked at 11 dig sites across North America and found elevated levels of platinum in very specific soil layers.

“The presence of elevated platinum in archaeological sites is a confirmation of data previously reported for the Younger-Dryas onset several years ago in a Greenland ice-core,” Christopher Moore, the lead author of the study, told the Archaeology News Network.

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This ‘Younger-Dryas’ period is best known as one of extreme cooling that began around 12,800 years ago and lasted for roughly 1,400 years.

This period coincided with the end of the Clovis culture and the extinction of over 35 species of Ice Age animals, including woolly mammoths, mastodons and saber-tooth tigers. But why would they die out if they had already managed to survive through an ice age

“Platinum is very rare in Earth’s crust, but it is common in asteroids and comets,” Moore said.

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In other words, North America may well have witnessed an extinction-level event similar to the one that killed the dinosaurs, but one third of its size.

“It is continental in scale – possibly global – and it's consistent with the hypothesis that an extraterrestrial impact took place," Moore added.

While the scope of the current research has only determined the presence of anomalous platinum at multiple dig sites, it does provide a logical hypothesis that warrants further study.

Additional research could also help to identify potential impact craters responsible for the mass extinction.