Reporting in the journal Science,
Paul Sereno, Ricardo Martinez and colleagues describe Eodromaeus murphi.
This dinosaur was four feet long, fifteen pounds and lived 230 million-years-ago, just a few million years after dinosaurs first evolved. It looks similar to its contemporary Eoraptor,
except for its long canine teeth, suggesting the newly-discovered dinosaur is an ancestor of the predatory dinosaurs, including T. rex.