A pivotal new dinosaur study is finally settling a fierce, four-decade-long debate: Was the small tyrannosaur Nanotyrannus a distinct species or merely a teenage Tyrannosaurus rex? Now, a remarkably complete fossil reveals that Nanotyrannus was real.
For years, key fossils were thought by many paleontologists to be juvenile examples of Tyrannosaurus rex, which lived between 67 million and 66 million years ago in western North America. Rather than settling all arguments, however, this "nano" discovery opens a new chapter in understanding T. rex biology and further debate.
