Canadian researchers used fossilised teeth to identify as many as 23 species of small meat-eating dinosaurs that roamed in western Canada and the US, 85 to 65 million years ago.
Until now, only seven species of small two-legged meat-eating dinosaurs from the North American west had been identified.
University of Alberta palaeontologist Philip Currie and student Derek Larson examined a massive dataset of fossil teeth that included samples from members of the families to which Velociraptor and Troodon (possibly the brainiest dinosaur) belong, the journal Public Library of Science ONE reports.
"Small meat-eating dinosaur skeletons are exceedingly rare in many parts of the world and, if not for their teeth, would be almost completely unknown," said Larson, according to an Alberta statement.
The researchers say the huge increase in the number of small meat-eating species to 23 shows that instead of a few species existing for many millions of years, there were actually many small meat-eating species, each existing for shorter periods of time.
"We can identify what meat-eaters lived in what geographic area or geologic age," explained Currie. "And we can do this by identifying just their teeth, which are far more common than skeletons."