The Antiquity of Pachyrhinosaurus

For those of you relatively unfamiliar with ceratopsian dinosaurs, Pachyrhinosaurus may be an unfamiliar name. It's one of my favorite dinosaurs, partially because it's one of Alaska's Mesozoic saurians. It's also just plain wierd--instead of horns, Pachyrhinosaurus has a bony boss, like that of a musk ox or bison, except over its nose instead of its forehead. There are two known species: Pachyrhinosaurus lakustai is the better-known of the two and is represented by hundreds of bones and dozens of individuals. It was only recently named and described, in 2008. This is what it looks like, more or less:


Notice the spikes and bosses. This was a strange-looking ceratopsian, fo' reel, yo. But it's the second species named. The first species--and the genus--was named back in 1950 by Charles Sternberg. It is Pachyrhinosaurus canadensis, and our man Charles named a whole new family based on the holotype skull, since as he could not easily fit it into the Chasmosaurinae or Centrosaurinae,* so he erected the Pachyrhinosauridae for his new critter. P. canadensis actually doesn't look too horribly different from P. lakustai, but Sternberg was working with a partial skull and didn't really know what to make of this hornless wonder. So he crafted a 1/6th scale clay model for all to see, shown below:


It looks like a Protoceratops with a handy plate to put your drink on its nose. It's also smiling. Still, this is important: here we have the first life restoration--crude though it may be--of this most bizarre ceratopsid dinosaur. I very much like Sternberg's description of the beast:

"The specialized development, the large massive head and the great thickness of bone is suggestive of the freakish development that took place among some of the dinosaurs near the very close of the Cretaceous, about Lance time."

Well put, Charles, well put. You didn't know the half of it....

*Back then, the Ceratopsia was a sub-order, divided into two familiest: Chasmosauridae and Centrosauridae, so Sternberg erected a third family. Today, we recognize the Ceratopsidae as a family, with the Chasmosaurinae and Centrosaurinae as sub-families. Sternberg's Pachyrhinosaurus-centric group still exists, however, as the Pachyrhinosaurini, which includes both species of Pachyrhinosaurus and Achelousaurus.