Looks like the bones they found in the Iowa River are prehistoric:
Jawbone found in Iowa River belonged to prehistoric human
"The Office of the State Archaeologist determined the bone belonged to a prehistoric Native American of middle to older age. More research will be done to determine what tribe had a camp on the north side of the river."
Jawbone found in Iowa River belonged to prehistoric human
"The Office of the State Archaeologist determined the bone belonged to a prehistoric Native American of middle to older age. More research will be done to determine what tribe had a camp on the north side of the river."