Brandon Theurer

The Hindlimb and Pelvis of Ceratopsid Dinosaurs

Brandon Theurer visited the department to talk about his research as a graduate student at the University of Alberta. Theurer is a BYU geology alumnus, having graduated in geology with an emphasis on paleontology. He currently works closely with renowned paleontologist Dr. Corwin Sullivan, studying the leg and pelvis of Ceratopsid dinosaurs.

Theurer illustrated the nature of his research with an example. Imagine a friend explains to you that they have been studying human evolution. The research they've conducted is very thorough, but you begin to realize that they are only talking about the skull, completely neglecting the rest of the skeleton. You wonder how they can tell the difference between humans and similar animals, like orangutans, and they explain that the most important differences are found in the skull. You know, however, that the locomotion of monkeys is much different from that of humans, and you doubt that it only has to do with the skull.

Such is the case with horned dinosaurs. When studying the Chasmosaurine and Centrosaurine families of dinosaurs, paleontologists tend to only examine skull fragments because they believe that the postcrania between the species are largely the same. Theurer argues that Chasmosaurines, which include species like the Triceratops and Chasmosaurus, have subtle but impactful physical traits in places besides the skull that separate them from Centrosaurus, which includes such species as the Pachyrhinosaurus and the Centrosaurus. Understanding and defining these differences gives us a clearer picture of what these dinosaurs might have looked like and how they would have moved.

So far, Theurer has found thirty noticeable variations between the different horned dinosaur species by examining bones in the pelvis, leg, and foot. He took careful consideration when examining the ankles of these dinosaurs, seeking to understand exactly how they would have walked. When studying the knees, he noticed that the traditional way of placing the bones in an upright position left an inexplicable gap that didn't make sense. By using 3D imaging and computer modeling software, Theurer was able to create a model that better fits the two largest bones of the leg together. Instead of standing upright, his model suggests that these prehistoric animals stood more in a semi-sprawling position, closer to that of a lizard. Though somewhat controversial, Theurer believes that his model better reflects what these dinosaurs would have looked like and how they would have walked.

If you would like to learn more about paleontology, visit the BYU Museum of Paleontology today!