Dinosaur

Iguanodon dinosaur bone, lower cretaceous period, 142 million years old

Although dinosaur footprints are relatively common in the Purbeck Beds of Dorset, dinosaur bones such as this iguanadon limb are very rare. The reason is suprisingly simple and obvious. Iguanadons only had two legs, but each animal made millions of footprints in its lifetime, so there were far more footprints than bones.