( CNN ) -- Tiny diamonds found in the soil are `` strong evidence '' a comet exploded on or above North America nearly 13,000 years ago , leading to the extinction of dozens of mammal species , according to a study . Diamonds found in North American soil suggest a comet led to the extinction of dozens of mammal species . The scientific report also suggests the cataclysm also reduced the population of the earliest people to inhabit the region and triggered a 1,300-year-long cold spell that stretched around the world . The heat generated by the extraterrestrial impact likely melted much of a glacier that once covered the Great Lakes region , sending a massive flood down the Mississippi River , the study said . According to the report , the cold waves of glacial runoff into the Gulf of Mexico shifted Atlantic Ocean currents , changing climate patterns throughout the world in a cooling period known as the Younger Dryas . `` A rare swarm '' of comets rained over North America about 12,900 years ago , sparking fires that produced choking , leading `` to the extinction of a large range of animals , including mammoths , across North America , '' the report said . The study was conducted by a group of eight archaeologists and geologists from the universities of Oregon and California , Northern Arizona University , Oklahoma University and DePaul University . Their findings were published Friday in the journal Science . iReport.com : Have you ever seen a comet ? Show us . The prehistoric humans known to have inhabited the continent at the time of the event -- hunters and gatherers dubbed the Clovis culture -- suffered a major decline in population in the aftermath , the scientists said . The scientists studied layers of sediment dated to 12,900 years ago at six North American locations , including one directly on top of a Clovis site in Murray Springs , Arizona . Each layer was rich in nanodiamonds , which are produced under high-temperature , high-pressure conditions created by cosmic impacts , the report said . `` 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 , '' said University of Oregon archaeologist Douglas Kennett . `` 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 . '' The other sites studied were in Bull Creek , Oklahoma ; Gainey , Michigan and Topper , South Carolina , as well as Lake Hind , Manitoba ; and Chobot , in the Canadian province of Alberta .
Study : Diamonds found in North America links comet to climate change , extinction . Prehistoric humans also suffered decline in population due to cosmic event . Heat from comet 's impact likely melted glacier that once covered Great Lakes region .