About 67 million years ago, in what is now north-west Montana in the United States of America, a dinosaur died. Some thought it might be a Nanotyrannus, a kind of pygmy relative of the mighty 13m-long Tyrannosaurus rex. Others believed it was a juvenile T. rex that died too young – and that there was never any such species as Nanotyrannus. As many palaeontologists are coming to realize, to understand the Age of Dinosaurs, you first have to understand the age of the dinosaurs you are studying.
http://www.bbc.com/earth/story/20160816-meet-nanotyrannus-the-tyrannosaur-that-never-really-existed
