Spiral Fractures and Bone Pseudotools at Paleontological Sites

Abstract
Spiral ("green bone") breakage has been suggested as an indicator of human activity by some workers. Our examination of broken ungulate long bones from six paleontological localities in western Nebraska, however, shows that such fractures commonly occurred in the Miocene and Pliocene, long before the advent of man in North America. Pseudotools also occur frequently in these sites. We postulate that spiral breakage, including the production of pseudotools, may be due to trampling by animals.Our study demonstrates that neither spiral breakage nor gross morphology, alone or in combination, is diagnostic of human activity. Problematical examples must be accepted or rejected wholly upon the basis of patterned wear on the supposed tools.