Treasure Coast amateur fossil collector James Kennedy appears to have made an unprecedented archaeological discovery that might help confirm a human presence here up to 13,000 years ago.

A 15-inch-long prehistoric bone fragment found near Vero Beach contains a crude engraving of a mammoth or mastodon on it, said Dr. Barbara Purdy, emeritus professor of anthropology at the University of Florida.

The only comparable images are found in European cave paintings, she said in an interview Friday. The bone contains "the unmistakable incising of an ancient proboscidean [elephant]," she said.

Kennedy found the brown and tan bone two years ago and put it under his sink. About two months ago, he took it out for cleaning and spotted unusual lines. He had been considering selling it at a flea market.

Instead, he showed it to a fellow collector, William Roddenberry of Vero Beach, who was amazed. They took it to the Florida Museum of Natural History in Gainesville for examination.

This month, a Florida State University archaeologist is leading a team that is taking soil samples from the site at the administration building. That is in preparation for a scientific excavation there next year to help try to settle whether or not humans co-existed here with mammoths and other extinct species.