When Englishman William Buckland found a large tooth in 1824, scientists began to unravel the mystery a world no one knew existed.
Cronkite heads to Montana, Wyoming and Utah, where dinosaur bones were discovered in the 1870s.
A dinosaur egg was found in the Gobi Desert in 1922. More eggs were found later in a nesting site in Montana.
The story of an unusual dinosaur with feathers found in Germany in 1861.