Discovery Day

Monoclonius was discovered and described and named by Edward Drinker Cope in 1876. Since then we know that all of the species in the genus have been shuffled about and claimed by other genera. This confusion began with the discovery of the animal itself. When initially discovered, the skeleton consisted of few bones and a partial skull. Cope initially believed that the skeleton and skull belonged to a hadrosaur and named the animal based on its teeth as it did not have a horn by which to name it. Therefore, any source which mentions the name meaning "one horn" is actually very incorrect. The name actually refers to the roots of the teeth of the animal and means "one sprout" in reference to the manner in which the teeth grew in a single set to be replaced when mature teeth were worn out rather than having two sets of mature and immature teeth growing in at the same time in the animal's mouth. Cope, however, did fix his own mistake after reading Marsh's description of Triceratops, realizing that Monoclonius was a ceratopsian dinosaur and not a hadrosaur. In 1904 Lambe began comparing his newly discovered Centrosaurus with Monoclonius, and thus began the long slide of Monoclonius out of the good graces of being a true genus!