Clovis Spear Straightener Clovis hunters used this bone spear straightener about 11,000 BP at a campsite in Arizona, where archaeologists discovered it lying among the butchered remains of two mammoth carcasses and thirteen ancient bison. Clovis hunters stuck their spear shafts through the opening and then moved the spear straightener back and forth along the length of the spear shaft. Arizona State Museum, University of Arizona.