Pachycephalosaurus:The Sequel—The Fossil Presence of Keratin.
I was checking my deviantArt messages when I saw the piece of artwork you see above this text. http://malvit.deviantart.com/ is the illustrator, and here he has depicted a pair of jousting Pachycephalosaurus, a dinosaur that I have spoken of before. This is one of his most recent illustrations, inspired by the book All Yesterdays. I’m sure you’ll notice what’s different about it compared to other reconstructions of Pachycephalosaurus. Yes, you do. It’s got keratin horns atop its characteristic domed horns. Experts (such as Gregory Paul) have said that the presence of keratin horns on bosses and domes cannot be eliminated (In this case Paul was talking about Pachyrhinosaurus), because keratin doesn’t preserve. In All Yesterdays, C.M. Kosemen illustrated a magnificent “shrink-wrapped” rhinoceros, which had no horn or external ears, and the extended vertebrae on its back were interpreted (hypothetically, by hypothetical paleontologists of the future) as representing a sail, probably a way to poke a bit of fun at the fact that the majority of experts maintain that dinosaurs like Spinosaurus and Ouranosaurus possessed sails on their backs. But I’m getting off track here.
Anyway, there was a pretty good explanation for this keratin-adorned pachycephalosaur duo. Though the initial hypotheses about their domes suggested that these animals knocked skulls like bighorn sheep, but John Horner suggests that the skull of the animal couldn’t resist such a frontward collision with another animal’s head. As it still seems that the skull was specifically adapted to bear the weight of something heavy, MALvit suggests that the keratin horns, however strange-looking, may have served as the cranial adornments that pachycephalosaurs battled with. It doesn’t involve head-butting, but still involves head-jousting. In this way, it’s a bit more like the courtship battles of deer than those of bighorn sheep. It’s a plausible idea.
There are lots of competing hypotheses about what Pachycephalosaurus did with its skull dome, but this cool artist took it a step further and took the dome out of the picture, covering it in keratin pseudo-antlers. Kudos to him for this, and kudos to him for giving the creatures hair-like feathers.