T-rex teens fill mid-size predator gap

Few animals inspire the imagination like Tyrannosaurus rex. And the mighty tyrannosaurs did dominate the lands that eventually became central Asia and western North America for millions of years. But during that time, fossils show that medium-sized predators all but disappeared. Why? Thomas Holtz from the University of Maryland dug deep into the records, and - as he tells Charlotte Birkmanis - thinks teen T-rexes are the answer...