A Patreon request for rome.and.stuff (Instagram) - Pachyrhinosaurus perotorum… that I went a bit overboard with lol. I’ve been waiting for an excuse to draw my favorite ceratopsian, and to digitally adapt my old Pachy marker drawing design.
So! Pachyrhinosaurus! As seen above, there were three known species of Pachyrhinosaurus, living in different locations and eras in Late Cretaceous North America.
The oldest, P. lakustai, was native to the Wapiti Formation of Alberta and British Columbia, Canada. It’s known for the extra spikes it has at the center of its frill.
The slightly younger P. canadensis was native to the lower Horseshoe Canyon Formation and the St. Mary River Formation of Alberta and northwestern Montana. It was the largest of the three.
The youngest, P. perotorum, was native to the Prince Creek Formation of Alaska. As this ceratopsid seemingly stayed put during the long, dark, cold Alaskan Winters, it likely had adaptations for keeping warm.
The depiction of a “woolly” Pachyrhinosaurus was first popularized by Mark Witton as a speculative work, but the trope has prevailed. While many paleontologists find a heavy feather covering on a centrosaurine to be highly unlikely, and maintain that the animal’s size and homeothermy would have kept it warm enough, we still have no skin impressions to suggest that P. perotorum was fully scaly. So a feather coating is not completely out of the question (though it is unlikely). Still, I love the look of a woolly Pachyrhinosaurus and how it challenges our previous conceptions of non-avian dinosaurs. Stranger things exist in nature. I had to include a “woolly” option, especially since I already use the guy as my avatar on my paleo Instagram account, SaritaPaleo.
Pachyrhinosaurus was particularly unique in that it seemingly traded off something that had previously worked for other ceratopsians, horns, for a large nasal boss instead. For Pachyrhinosaurus, a battering ram worked better than a sword.
It was herbivorous, using its strong cheek teeth to chew tough, fibrous plants. Perhaps during the dark and cold Winters, P. perotorum would have also dug for roots or even scavenged carcasses. At any rate, from observations of their unusually conspicuous growth banding, it appears growth for P. perotorum would have been stunted during the harsh Winter, but was extremely rapid in the warmer months, an adaptation for the Alaskan climate.
The tundra of the Prince Creek Formation housed a surprising amount of diversity. Pachyrhinosaurus perotorum would have lived alongside smaller ceratopsians like Leptoceratopsids, as well as other ornithischians like the pachycephalosaurine Alaskacephale and the hadrosaurid Edmontosaurus. Theropods such as Dromaeosaurus and Saurornitholestes, as well as a yet unidentified giant Troodontid, lived here as well. P. perotorum’s main predator would have been the tyrannosaur Nanuqsaurus. Small mammals were also somewhat common here, such as Cimolodon, Gypsonictops, Sikuomys, Unnuakomys, and an indeterminate marsupial.
(Btw, the request tier for Patreon starts at only $5 a month. 😉 Link is pinned at the top of my blog.)
Is it only me that thinks that Diabloceratops and Machairoceratops could be basal to Ceratopsidae? Since both are more derived-looking than Zuniceratops or Turanoceratops, but more basal than like Nasutoceratops or Kosmoceratops. Could it be possible Machairoceratops and Diablo are late surviving basal Ceratopsoids?
maybe, it's not that many steps from where they are now, but they do firmly come up in centrosaurinae in most analyses. I'd have to look at the paper for the confidence levels / statistical analysis of that placement, though.
SINOCERATOPS
“Chinese horned-face”
Late Cretaceous, 72-66 million years ago
This large centrosaurine dinosaur had one large nasal horn, with myriad small, curved hornlets lining its frill. It is notable for being the only true ceratopsid in all of Asia (despite ceratopsians as a whole likely originating there). Such conjecture gave rise to the presiding “Styracosaurus in witness protection” theory.
Our Mexican dinosaur spree continues! Presenting a herd of mid-sized chasmosaurine ceratosians from the region of Aldama, Chihuahua, Mexico indicates that there were more species relative to Nasutoceratops. The Museo del Mammutin the northern state of Chihuahua has tried this reconstruction, but with the clear exception of the frill and some other cranial fragments, the museum present us here…
Pachyrhinosaurus was a large (25-foot-long) ceratopsian dinosaur from North America. At least three distinct species are known, the fossils of which have been found in Alberta and Alaska - although not in between. It may have seasonally migrated between the two locations, although that’s just my own theory.
(A pair of Pachyrhinosaurus, by James Havens.)
Unlike most ceratopsians, Pachyrhinosaurus had no horns over its eyes or nose. Instead, it had large, bony “bosses” in those locations. The exact shapes of these structures, as well as the arrangements of ornamental spikes, horns, and nodules on the frill, differed from species to species. These blunt structures were likely less useful for defense against predators than the horns of, say, Triceratops; they may have been used for “head-butting”, in order to compete with other members of their species. They might even have been anchor points for keratinous structures, like the horns of a rhinoceros! Again, however, that’s just my own theory.
(Pachyrhinosaurus using their nasal bosses to headbutt one another. By Karen Carr.)
Pachyrhinosaurus lends its name to the tribe Pachyrhinosaurini. The members of this tribe, the pachyrhinosaurines, are united by their reduced horns in comparison with other large ceratopsian species. Einiosaurus’ nose horn was a forward-pointing “can opener”, while Wendiceratops, discovered only in 2015, had a broad nose horn with a blunted tip. It’s unknown why the members of this family had such odd-looking horns and bosses; since the pachyrhinosaurines are members of Centrosaurinae, a ceratopsian clade known to have used its horns more for display than combat, its possible that they were the results of a trend away from defense and towards display.
