This is the third of five blogs by Jordan Mallon, Ph.D., that profiles the fossils featured in the museum’s Dino Idol competition. From February 16 to March 17, 2013, visit the Canadian Museum of Nature and choose your favourite from among the five dinosaurs whose bones are sealed away in plaster field jackets.

Illustration of an Arrhinoceratops.
The skull of Stumpy may have belonged to a rare ceratopsid called Arrhinoceratops, depicted here. Image: Brett Booth © Canadian Museum of Nature

This is the third of a five-post series detailing the specimens to be voted on for our Dino Idol contest.

The next specimen I would like you to consider voting for is Stumpy, affectionately named by our fossil collections technician, Margaret Currie. This is the skull of a horned dinosaur (ceratopsid) collected by the field crew of Charlie M. Sternberg near the town of Morrin, Alberta, in 1924.

The skull was collected in three parts: the main skull block, including the eye sockets and bony cheeks, is in one jacket; the snout is in another; and the conspicuous head frill was collected in pieces wrapped in old newspaper.

Sometime after the skull was collected, the main skull block was partially prepared, revealing a very interesting feature: this ceratopsid appears to have resorbed its right brow horn! There is now only a small pit above the eye the size of a loonie where the horn once was. The left brow horn, however, is fully developed, though broken at its base.

The partially prepared plaster jacket that contains Stumpy.
The partial skull of Stumpy, viewed from the right side. The red arrow points to the loonie-sized depression where the right brow horn once was. The larger hole below that is the eye socket. To the right is the front of the face (where the snout would attach). To the left is the back of the head (where the frill would attach). Image: Robert Holmes © Canadian Museum of Nature

The phenomenon of horn-resorption is pretty common in short-horned ceratopsids (called centrosaurines) such as the Styracosaurus on display in the museum’s Talisman Energy Fossil Gallery, but is rarely seen in longer-horned forms (called chasmosaurines) like our friend Stumpy. If we can more fully prepare this specimen, it would be interesting to study how horn cores were resorbed, perhaps with the help of computed tomography (CT scan).

A man squats in front of a rock face, lifting a wet plaster-covered cloth from a bucket beside a plaster field jacket.
If it weren’t for plaster field jackets, specimens like Stumpy would’ve never made it back to the Canadian Museum of Nature intact! This image shows the youngest member of the Sternberg field crew, Levi, putting the final touches on a field jacket. Image: Charles H. Sternberg © Canadian Museum of Nature

When this specimen was first collected in the field, it was thought to represent a species that was new to science. However, based on certain untold features of the skull, Charlie M. Sternberg later noted that it probably represents an already-known, though rare, ceratopsid called Arrhinoceratops.

This animal lived on the floodplains of Alberta nearly 72 million years ago, alongside the likes of Albertosaurus (a tyrannosaurid) and Hypacrosaurus (a duck-billed dinosaur visible in the fossil gallery).

Stumpy on display in the museum.
Stumpy is hoping to get your vote in the Dino Idol contest. Image: Dan Smythe © Canadian Museum of Nature

I’m nearing the end of a study on Arrhinoceratops, and am confident that if we can finish preparing Stumpy, we should be able to confirm its identity. Whatever it turns out to be, Stumpy will make a valuable addition to the collections of the Canadian Museum of Nature, but only if it gets enough of your votes!

Please stay tuned next week, when we’ll be taking a look at our fourth fossil contender, Canadian Club…

Read previous blogs about the Dino Idol contestants:
Dino Idol Contestant #1: Headrosaur—A Head without a Body!
Dino Idol Contestant #2: Mystery Jaw—A Carnivore in Search of an Identity