An oil company drilling in western Oklahoma has stumbled across a deposit of camel and horse fossils that date back roughly five million to 12 million years, scientists who've examined the remains say.

The fossils, which belong to long-extinct species of camel and horse, were found in July in the Packsaddle Wildlife Management Area.

An alert heavy-machine operator working for Apache Corp., the Houston-based oil company drilling in Packsaddle, discovered the long-hidden fossils after he'd cleared away roughly 20 feet of earth.

Some of the fossils are in good condition — relatively speaking — with the highlight being a well-preserved horse skull far tinier than its present-day descendant.