Tyrannosaurus rex may have been three species

Tyrannosaurus rex might not have been one species, but three. Palæontologists studying 37 T. rex specimens say there is too much variation in their ‘stout build’ and teeth to be a single species. Instead, they propose that fossils found in lower layers of rock are probably from a species they call Tyrannosaurus imperator, and slender-boned specimens are likely from a creature they’ve named Tyrannosaurus regina. The work has prompted widespread discussion, but many palæontologists are not convinced.