Stygimoloch

Type Species: Stygimoloch spinifer

Classification: Dinosauria - Ornithischia - Marginocephalia - Pachycephalosauridae - Pachycephalosaurini

Time Period: late Cretaceous

Location: North America

Diet: Herbivore

A contemporary of my favorite dinosaur Parasaurolophus, my second favorite dinosaur is this wicked-looking devil to the left. His name means "the horned devil from the river of Hell," since (a) it's a horny bastard and (b) lots of its remains have been found in the Hell Creek Formation in Montana (the sty is inspired by the River Styx in classical mythology; moloch is derived from the pagan god by the same name, who would be identified by Judeao-Christian sources as "the Devil"). 

Stygimoloch was a medium-sized pachycephalosaur, dwarfed by its relative Pachycephalosaurus, the most widely-known pachy of them all! This guy's skull was decorated with horny bumps, piercing horns, and spikes; it also had the domed skull, a signature of the pachycephalosaurs. The horns ran from the base of the dome to the snout. The skull horns may have been used for butting enemies in dire circumstances, or maybe even in mating rituals, but because the horns are relatively weak, they were probably used solely for courtship displays. The horniest Stygi got the chic. Here's a size comparison between a human being and our Dino of the Week:

Interesting fact: rather recently, some paleontologists have started advocating the idea that Stygimoloch is simply the juvenile version of Pachycephalosaurus. That's an interesting take, but I hope they're wrong: I don't want to find a new 2nd Favorite Dinosaur.