Prehistoric human jawbone found in Iowa River

A jawbone that was found in Iowa last month belonged to a prehistoric man, authorities have determined.

On Aug. 11, the Marshall County Sheriff's Office said conservation staff found a possible human lower jawbone in the Iowa River. While it was intact, officials said it had deteriorated to the point that they believed it was a few years old. Three other potential human bones were also found in the area.

The Marshall County Medical Examiner was contacted, and authorities began investigating the findings.