R. Nial Bradshaw/U.S. AirforceR. Nial Bradshaw/U.S. Air ForceResearchers found 88 fossilized footprints in Utah By Rachel Fadem, CNN Research on ancient footprints has previously challenged what’s known about when people arrived in North America, and a new discovery could shed more light on the story. Scientists have found 88 fossilized prints belonging to adults and children, likely dating back 12,000 years, in shallow riverbeds on the US Air Force Utah Test and Training Range. This is only the second set of human tracks from the Ice Age to be identified in what is now the United States.