For dating, eggshells are better
But ash is not always current. In Africa, nonetheless — and before the Holocene, through the center East and Asia — ostrich eggshells are common. Some web sites also contain ostrich eggshell ornaments produced by early Homo sapiens.
Elizabeth Niespolo, during the time a graduate student in UC Berkeley’s Department of world and Planetary Science, splitting uranium from thorium in a lab at the Berkeley Geochronology Center. (Picture by Warren Sharp, BGC)