Centrosaurus

Name: Centrosaurus (Greek for "pointed lizard"); pronounced SEN-tro-SORE-us

Habitat: Woodlands of western North America

Historical Period: Late Cretaceous (75 million years ago)

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Monoclonius

By Bob Strauss

Size and Weight: About 20 feet long and three tons

Diet: Plants

Distinguishing Characteristics: Single, long horn on end of snout; moderate size; large frill over head

About Centrosaurus

It was probably too dumb to notice the difference, but Centrosaurus was definitely lacking when it came to defensive armament: this ceratopsian possessed only a single long horn on the end of its snout, compared to three for Triceratops (one on its snout and two over its eyes) and five (more or less, depending on how you're counting) for Pentaceratops. Like others of its breed, Centrosaurus' horn and large frill probably served dual purposes: the frill as a sexual display and (possibly) a way to dissipate heat, and the horn to head-butt other Centrosaurus adults during mating season and intimidate hungry raptors and tyrannosaurs.

Centrosaurus is known by literally thousands of fossil remains, making it one of the world's best-attested ceratopsians. The first, isolated remains were discovered by Lawrence Lambe in Canada's Alberta province; later, nearby, researchers discovered two vast Centrosaurus bonebeds, containing thousands of individuals of all growth stages (newborns, juveniles, and adults) and extending for hundreds of feet. The most likely explanation is that these herds of migrating Centrosaurus were drowned by flash floods, not an unusual fate for dinosaurs during the late Cretaceous period, or that they simply perished of thirst while gathered around a dry water hole. (Some of these Centrosaurus bonebeds are interlaced with Styracosaurus fossils, a possible hint that this even more ornately decorated ceratopsian was in the process of displacing Centrosaurus 75 million years ago.)

Recently, paleontologists announced a pair of new North American ceratopsians that seem to have been closely related to Centrosaurus, Diabloceratops and Medusaceratops, both of which sported their own unique horn/frill combinations reminiscent of their more famous cousin (hence their classification as "centrosaurine" rather than "chasmosaurine" ceratopsians, albeit ones with very Triceratops-like characteristics as well). Given the profusion of ceratopsians discovered in North America over the last few years, it may be the case that the evolutionary relationships of Centrosaurus and its nearly indistinguishable cousins have yet to be fully sorted out.