The place:
The Hell Creek Formation lies east of the Rocky Mountains in Montana, USA. Today it is a semi-arid region with numerous exposed outcrops of rock which are being constantly eroded to expose more fossil remains.

The finds:
The Hell Creek Formation contains the remains of some of the very last dinosaurs including Tyrannosaurus, Ankylosuarus, Anatotitan, and Torosaurus. Recently Hell Creek has proved useful for a different reason. It is the only dinosaur-bearing fossil bed that crosses what is known as the K-T Boundary, the period straddling the great dinosaur extinction.

The environment:
In the Late Cretaceous period the area was a broad, low-lying plain, crossed by several narrow rivers and bordered by an inland sea. The climate is thought to have been mild with a high rainfall. The rivers were periodically subject to flash floods which have served to concentrate dinosaur remains. Tree remains are not common so forest cover was probably limited to the river banks.

The people:
The Hell Creek formation's most famous dinosaur is probably Tyrannosaurus, the largest ever land predator. In 1906 Henry Fairfield Osborn described Tyrannosaurus and coined the name, after studying two reasonably complete skeletons found at Hell Creek.