Piecing Together the Skull of Daspletosaurus

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 left maxilla (upper jaw). Note the teeth at various stages of growth. Dinosaurs continually replaced their teeth throughout their lives.

The left maxilla (upper jaw). Note the teeth at various stages of growth. Dinosaurs continually replaced their teeth throughout their lives.

A close-up of tooth growth in the upper left jaw.

A close-up of tooth growth in the upper left jaw.

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.

3-DaspletoFieldCrew-WP

A field crew at work excavating Daspletosaurus torosus.

A 2001 map of the quarry where Daspletosaurus torosus was found. Note the maxilla (upper jaws) on the right side of the map.

A 2001 map of the quarry where Daspletosaurus torosus was found. Note the maxilla (upper jaws) on the right side of the map.

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.

The left pre-maxilla (front of the upper jaw) in the field.

The left pre-maxilla (front of the upper jaw) in the field.

Left pre-maxilla (front of the upper jaw) prepared.

Left pre-maxilla (front of the upper jaw) prepared.

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.

Isolated teeth from Daspletosaurus torosus.

Isolated teeth from Daspletosaurus torosus.

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.

8-HumanSkull-WP

An exploded human skull. Exploded skulls are used as an anatomy tool to show all the bones that make up the skull.

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.

In the upcoming months, we will be explaining the process of 3D printing a cast and how we built a mount to display the exploded skull. The exploded skull cast of Daspletosaurus torosus will be going on display in Fossils in Focus on February 16.

An interpretive model of what the skull of Daspletosaurus torosus would look like as an exploded skull.

An interpretive model of what the skull of Daspletosaurus torosus would look like as an exploded skull.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s