Workers digging at a downtown San Diego construction site have uncovered the prehistoric remains of an 8-foot-long mammoth.

A backhoe operator working at the Thomas Jefferson School of Law site unearthed a 20-foot-long tusk Wednesday.

School spokesman Chris Saunders says experts called in from the San Diego Natural History Museum uncovered the animal's skull and other bones.

Museum paleontologist Pat Sena says it's a "pretty important find" and that it's rare to find mammoth remains with such an intact skull, foot bones and tusk.

Full-sized mammoths, about 8 to 14 feet tall like elephants, became extinct around 10,000 years ago. But experts believe the specimen found this week dates back as far as a half-million years ago.