With a dental pick in hand, Karin Rice delicately scraped off a clump of asphalt from a pelvic bone belonging to a horse that roamed Los Angeles tens of thousands of years ago.

Like many unsuspecting creatures of the last Ice Age, the horse probably stopped to take a sip of spring water only to be ensnared — and later preserved — in a pool of sticky asphalt that seeped from underground crude oil deposits.