A spear tip embedded in a mastodon rib indicates that humans were hunting in North America 13,800 years ago – 800 years earlier than previously thought, the Guardian reports.

The projectile, made of bone or antler, was first analyzed by archaeologist Carl Gustafson in the 1970s. He proposed that it was man-made and about 14,000 years old. However, at the time, it was believed that humans hadn’t arrived in North America at that point, and his ideas were widely dismissed. Other explanations for the bone was that it was a part of the mastodon's skeleton or a bone chip from a fight with another animal, LiveScience reports.

A few years ago, Professor Michael Waters from Texas A&M University arranged to reexamine Gustafson’s mastodon specimen using a CT scanner. "The 3D rendering clearly showed that the object was sharpened to a tip,” Waters told the Guardian. “It was clearly the end of a bone projectile point." Modern dating technology put the age of the specimen at 13,800 years old.

"Clearly these people were hunting mastodons, and probably harvesting their bones to make tools," Waters, who has published his findings in the journal Science, told the Houston Chronicle. "It adds one more piece to the puzzle of trying to understand the first Americans. It's filling out our picture."

According to the Houston Chronicle:

Since the 1930s, archaeologists had believed the ancestors of the Clovis people - so named for a small number of stone "points" found near Clovis, N.M. - walked into North America from Asia across the Bering Sea landmass as the last Ice Age waned about 13,500 years ago. But several finds in recent years, including Waters' excavation of a site just north of Austin, have overturned this theory.

Newly discovered artifacts suggest that the first Americans traveled from Asia along the Alaskan and Canadian coasts in boats 16,000 years ago, the Houston Chronicle reports. They also imply they may have hastened the North American extinction of mastodons, mammoths and other large mammals between 14,000 and 11,000 years ago.

