STEGOCERAS

Stegoceras is a pachycephalosaurid, a thick-skulled, bi-pedal leaf-eater, who may (or may not) have banged heads with rivals for mating rights a'la musk oxen and bighorn sheep. It was also the first of its kind to be discovered in North America. Unfortunately, no one realised this at the time.

When Lawrence Lambe named Stegoceras (horn roof) in 1902, he thought it was some sort of ceratopsian and that the thick, bony lump on top of its head was the stump of a damaged horn. Better specimens showed that not to be the case, and by 1918, Lambe thought its affinities lay with Stegosauria in a raised-for-the-occasion family that he called Psalisauridae. Soon enough, its teeth were being compared to those of another dinosaur, and Stegoceras was sunk as a synonym of Troodon in 1924 by Gilmore, who dismissed Lambe's Psalisauridae and proposed Troodontidae as a replacement name. But twenty-one years later, Charles Sternberg realized Troodon was a carnivorous theropod, and so he moved Stegoceras and its bone-headed relatives to their own family, Pachycephalosauridae, in 1945

Sporting a three-inch thick skull cap, Stegoceras looked like it was wearing a crash helmet, which, with added spikes, was an ideal tool for exerting one's dominance over lothario wannabes who were eyeing up your ladies. But top-speed head-to-head butts may have been suicidal, bearing in mind their curved necks weren't designed to absorb impact nor their domed skulls built for anything more than glancing blows, so they probably butted each other in the flanks instead. What's the point of winning a duel if you're too concussed to claim your prize?