Anchiceratops ornatus was a pretty successful dinosaur. The single known species of this elaborately horned herbivore survived for about two millions years during the Late Cretaceous—many thousands of years longer than the varieties of horned dinosaur which preceded it in prehistoric Canada. This is a recent realization. As I wrote last September, what were once thought to be two different species of Anchiceratops were actually one, and the idea that paleontologists have found both male and female forms of this dinosaur has also been struck down.
These changes stemmed from a better understanding of dinosaur variation. Often, small differences between dinosaur skeletons led paleontologists to establish new species or genera of dinosaur when those subtle variations were really just signs of individual disparity within a species. In the latest Royal Tyrrell Museum lecture, paleontologist Jordan Mallon, the lead author on the Anchiceratops paper, explains how he tracked variations among fossils to give us a better idea of dinosaur diversity and evolution.