the deposits of the area where the skeleton was found dated the site where tepexpan man was found to about 8,000 to 10,000 years ago. near the skeleton, there were the remains of five mammoths. they could be associated with obsidian flakes. therefore, it was originally believed that tepexpan man dated to about 10,000 years ago. however, years later, researchers looked at the skeleton again and dated the remains using radiocarbon methods. it was then found to be closer to 2,000 years old. dr. silvia gonzalez, a professor of geoarchaeology at john moore university in liverpool, used uranium isotope analysis to date the skeleton. results showed that tepexpan man was 4,700 years old. she argues that contamination of the remains led to the wrong radiocarbon dates. other critics have claimed that tepexpan man was an intrusion in that he was buried at a later date but dug into pleistocene materials.