How to find the history of dinosaurs in the wilds of Montana

Dinosaur bones have been shipped all over the world from Montana ever since the mid-1800s.

The geology and lack of vegetation in parts of the western US mean that fossils are never far from the surface, which is why so many are found there.

But what do scientists look for as they take their steps through the imposing landscapes of the American west?

The BBC's Jane O'Brien visits one such excavation site to find out.

Produced by Jane O'Brien and David Botti