Extinct Creatures-- Pachycephalosaurus

Whoo, it's been a while since I posted an extinct creature! Guess I got a little burnt out on drawing them after working on the Mesozoic book. But here we are with Pachycephalosaurus, one of my favorites! Though really, I think all dinosaurs are my favorites.

Pachycephalosaurus (pachy=thick cephal=head saur=reptile) is a dinosaur that lived in North America (hence the wyomingensis species name) in the late Cretaceous, right before the dinosaurs died out. The pachycephalosaurs didn't evolve 'til pretty late in the game, and Pachycephalosaurus is the largest yet found. They were herbivores known for the domes of bone on their heads which they probably used to charge other animals or even other pachycephalosaurs, though fossil evidence suggests they didn't engage in the classic "head-butting" behavior people know them for. There isn't much evidence of bone-on-bone trauma on the domes themselves, though that doesn't rule it out as something that occasionally happened.

There are two other types of very pretty pachycephalosaurs on this page-- Dracorex hogwartsia (the dragon king of Hogwarts) and Stygimoloch spinifer (the king of the river Styx).  Whoever was in charge of naming these creatures did a very good job. However, there is some debate in the paleo community about whether or not these two are actually distinct species, or whether they're growth stages of Pachycephalosaurus! As you can see in the drawings, Dracorex has no real dome to speak of, Stygimoloch has a slightly more pronounced dome, and Pachycephalosaurus has a big dome. Also, their sizes go in order from small to large. This is currently just a theory, but it's certainly an interesting one! There are clues in the fossils that are able to tell us whether a creature was still growing or was fully grown, but sometimes it takes more evidence to really be able to reach a solid conclusion. It's not as easy as it is with modern creatures, where you can just observe them to see what their babies look like. It's the same with sexual dimorphism-- sometimes we list the male and female as different species for a long time before we have enough evidence to determine that they're actually the same species!

Oh, and as for the protofeathers, those are pretty speculative, but I like to have fun so I gave it a nice little jacket. It's not far-fetched, though, as Kulindadromeus (an amazing little Ornithischian with a protofeather pattern not much different from this) is a close relative of pachycephalosaurs. And as they're so small, I'd assume it would be more help than trouble to have a nice fluffy covering to keep you warm on the cold plains at night.

That's all for now-- I might post a little comic before the week is up, but we'll see if I have time! Hope you're all doing well, and thank you for your patience.

Also you should pre-order my book  ;0

-Abby