Fossil Fingerprints: Rare earths tie bones to burial ground

In the summer of 2002, paleontologists traveled from Temple University in Philadelphia to Badlands National Park in South Dakota. There, they uncovered hundreds of fossils, among them 30-million-year-old specimens derived from ancient mammals and tortoises. Using measurements of cerium, europium, and other rare earth elements in the bones, the team uncovered even more: chemical signatures of the soil in which the fossils formed.