A paleontologist studying museum fossils has discovered two new species of horned dinosaurs that had been forgotten for the past 75 years. Ceratopsians were a group of mostly beaked and horned dinosaurs with bony frills, and included the adorable raven-sized Aquilops americanus, Mercuriceratops gemini with wing-shaped headgear, and of course Triceratops. This group first showed up around 140 million years ago in the Cretaceous and were among the last of the (non-avian) dinosaurs. The new findings, published in Cretaceous Research, suggests that the species varied a lot, even over short distances.
Nicholas Longrich from the University of Bath examined fossilized skeletons unearthed from southern Alberta that were previously classified as the Canadian ceratopsians Anchiceratops and Chasmosaurus. According to his reanalysis, however, they more closely resemble dinosaurs from the American Southwest.
The more complete specimen of the two is a new species of Pentaceratops—plant-eating, buffalo-sized dinosaurs with long brow horns that lived around 75 million years ago. Based on two fragments from the Dinosaur Park Formation near Manyberries in southeast Alberta, the newly named Pentaceratops aquilonius had a frill that was about 100 centimeters (39 inches) long. It’s closely related to Pentaceratops sternbergii from New Mexico, but it's smaller, more primitive, and had a different frill shape and hornlet arrangement on the back.
The other fossil, a partial skull from Dinosaur Provincial Park (a UNESCO World Heritage Site), likely represents a new species of Kosmoceratops. More complete fossils are needed to be certain, but it seems to be related to Utah’s Kosmoceratops richardsoni, which has a differently shaped nasal horn.
Pictured to the right are the locations of the new Kosmoceratops and Pentaceratops from Alberta, as well as related species from the western and southwestern United States. Specimens previously discovered in Colorado may also have belonged to Pentaceratops aquilonius.
The presence of the southwestern Pentaceratops and Kosmoceratops in Canada argues against the idea of distinct northern and southern faunal provinces during the Campanian period of the Cretaceous around 83 million to 72 million years ago. According to Longrich, after the dinosaurs dispersed long distances across the continent, they diverged to form new species, and then competition among the different species prevented them from moving between the northern and southern regions.
“With Cretaceous dinosaurs, we see a lot of large species in a single habitat. They also tend to be very regional,” Longrich says in a news release. “As you move from one habitat to another, you get a completely different set of species.”
Images: University of Bath