(Phys.org)—A trio of researchers, two with the University of Tübingen in Germany, the other the University of California has found evidence that suggests it is not possible to tell if marks on some ancient artifacts were made by ancient hominids using stone tools or by crocodiles. In their paper published in Proceedings of the National Academy of Sciences, Yonatan Sahle, Sireen El Zaatari and Tim White describe their study comparing bite marks made by stone tools and crocodiles, what they found by doing so, and what it might mean for research results made by other teams.