The Mystery of the Missing T. Rex Bones: New Study Estimates Up to 1.7 Billion Lived on Earth.

A new study suggests that 1.7 billion T. rexes lived on Earth from 65.5-68 million years ago, but scientists have only uncovered fewer than 100 fossilized T. rexes. The small number of fossils is due to the perfect set of conditions required for fossilization.