New research, published recently in the journal Science, seems to point at the fact that saber tooths, mammoths, giant sloths and camels, as well as the Clovis culture, were driven into extinction by a 1,300 year-long cold spell, triggered by numerous comet impacts in 6 states across the northern US and several in southern Canada.

As evidence to his claims, Doug Kennett, a researcher at the University of Oregon, brought numerous tiny diamonds, which experts say could have formed only under the high-temperature, high-pressure conditions that are characteristic to cosmic impacts, from comets or small asteroids.

This period of 1,300 years, already known as the Younger Dryas, is well-known to historians, but no one could say for sure what it was that caused it to happen. Kennett's theories seem to offer an answer to that question, seeing how only widespread fire and pressure could have caused these nanodiamonds to form.

UO researchers say that volcanoes are not responsible, as the area doesn't contain any capable of such widespread devastation. Rather, they believe that multiple comets or asteroids hit the Earth at very short intervals some 12,900 years ago, causing the meltdown of at least a part of Greenland's ice sheets, which in turn affected the flow of the oceanic currents, bringing about a small ice age.

Also, ash and dust risen up by the celestial bodies could have also covered the Sun, posing an extra danger to vegetation and animal species. Though the phenomenon was global, animal species in North America were most affected, as evidenced by the fact that there are relatively few fossils in the layers of ground above the threshold of the Younger Dryas.

"The nanodiamonds that we found at all six locations exist only in sediments associated with the Younger Dryas Boundary layers, not above it or below it. These discoveries provide strong evidence for a cosmic impact event at approximately 12,900 years ago that would have had enormous environmental consequences for plants, animals and humans across North America," Kennett explained in a statement.