Museum IDs New Species of Dinosaur

Uryugen writes "A new dinosaur species was a plant-eater with yard-long horns over its eyebrows, suggesting an evolutionary middle step between older dinosaurs with even larger horns and the small-horned creatures that followed, experts said. The dinosaur's horns, thick as a human arm, are like those of triceratops — which came 10 million years later. However, this animal belonged to a subfamily that usually had bony nubbins a few inches long above their eyes"

Moo

[Chacham]

Parlimentary inquiry.

How do we know this is indicative of an entire species, and not just a single freak of nature?