Experiencing the Ice Age in Real Time

Today through Sept. 10, visitors to the La Brea Tar Pits can watch the only active urban fossil excavation in the world--the annual Ice Age dig of Pit 91. Trapped in the sticky asphalt are fossils of wildlife that roamed the area from 10,000 to 40,000 years ago. Above, volunteer Sharen Dyer works around a giant ground sloth vertebrae (on her left) and a bison bone fragment. At right, a bison shinbone rises in front of paleontologist Lauren Michaelson.