This skull of Daspletosaurus torosus is one of the best-preserved theropod skulls in our collection. The skull is unique in that it is a disarticulated skull, where all the bones were found separately and were not crushed flat during fossilization. Daspletosaurus was a large tyrannosaur that lived 77.3 – 75 million years ago in Alberta and is closely related to Tyrannosaurus rex.
The skull bones of this Daspletosaurus torosus were first discovered in 2000 near the Milk River in southern Alberta, and it took until 2011 for all the pieces to be collected. Since the individual pieces of the skull were separated, it was not obvious where each bone was located in the quarry. Researchers waited until further pieces of the skull eroded out of the ground, rather than searching for them.
The skulls of all vertebrates (fishes, amphibians, reptiles, birds, and mammals) are made up of three main regions — the braincase, the bones on the outside of the skull covering the braincase, and the jawbones. These regions are made up of many smaller bones. Dinosaur skulls are the same as other vertebrates. The skull of Daspletosaurus torosus contains 41 individual bones that interlock together.
Although individual bones may not look as impressive as a complete skull, they contain a lot of information about a dinosaur. The skull is an important diagnostic feature that helps scientists identify dinosaur species or determine its nearest relatives. Many of the bones in a tyrannosaur skull are distinct enough that it is easy to identify a member of the family Tyrannosauridae with confidence.
As fossil bones are extremely fragile and often heavy, they can be difficult to manipulate and handle. That makes it difficult for researchers to study certain specimens, or for them to be displayed. Although we have the majority of the skull of Daspletosaurus torosus in our collection, it is too fragile to piece back together.
As a solution, we decided to create a cast and display it as an exploded skull. Exploded skulls are a common tool used to teach anatomy, allowing for examination of the individual pieces of a skull. This will allow researchers to examine all the bones that make up a theropod skull from multiple angles.
Since certain pieces of this skull of Daspletosaurus torosus are too delicate to be cast using traditional methods, we created a digital model of the skull using photogrammetry. By taking multiple photos of each piece, our technicians were able to create digital models of the skull that were then 3D printed. This project is the first time the Museum has 3D printed a cast of a specimen and it was very successful.
The exploded skull cast of Daspletosaurus torosus is currently on display in the 2018/19 edition of Fossils in Focus.