Activities - Skull

The skull is usually the most delicate part of a skeleton and is the part least likely to be found intact as a fossil. A skull is made from many fragile bones that easily fall apart after death.

One way crocs are different from most dinosaurs is that crocodile skulls are made from stout bones filled with teeth that fuse into a nearly solid block when the animal matures. The jaw muscles are buried deep in the skull, making a difficult meal for a predator. For that reason, we found many fossilized skulls of Sarcosuchus - more than any other animal in that part of the Sahara.

The largest skull we found was nearly perfect. The lower jaws were attached and many of the teeth were in their sockets. That's why we chose this 6-foot long skull as the model for the skull reconstruction you see below.

A. Skull (side view)
Some of Sarcosuchus' remarkable adaptations are easily seen in side view. Look at the teeth in the bone at the end of the snout (pm, premaxilla). Not only are they the largest teeth in the skull--the reverse of many crocodiles and alligators--they are angled inward. The longest bone in the cranium (m, maxilla) has 30 teeth. The tenth one is sort of like a canine, as it is noticeably larger than its neighbors.

B. Skull (top view)
Looking at the skull in "top view," it is easy to notice the extreme size of the nose opening! In life the opening of the nose, would have been surrounded by flesh, called the nostril, and would have appeared much smaller. The big opening enclosed a cavity, possibly for enhanced smell or for making unusual calls. Crocs are very communicative animals; they frequently roar, grunt, hiss and just splash around.
Also notice that the cavity for the eye, called the "orbit," faces upward and is in full view. This means Sarcosuchus' eyes were rotated more onto the top of the skull than in many living crocs.
The pair of holes behind each orbit is for powerful jaw muscles.

C. Cranium (view from below)
Now that we can see the skull upside down ("view from below"), where does the air come out when Sarcosuchus exhaled? Way back at the back end of the skull near its throat. Air passed in a tunnel inside the snout all the way to the back of the skull--surprise! The snout is hollow! Why have such an air tunnel inside the snout? This allows crocs to chew and breathe at the same time--just like us. It would be difficult for us to eat a meal if we needed to stop breathing with every bite!

D. Snout end (view from below)
Here is the fearful front end of the jaws of SuperCroc as seen from below. Look at that overbite! Those huge overhanging teeth and the fan-shaped end of the lower jaw are very unusual for a croc. They must have allowed this fearsome predator to grab anything it wanted to and drag it under the water.

E. Large tooth in mandible
This is an up-close look at the largest tooth in the lower jaws--tooth #3 (if we number the teeth from the front). It is a very strongly built tooth, only about twice as tall as it is wide. You can see the shape in the cross-section next to the tooth. Strong teeth like this are good for lots of things--catching fish but also for grabbing and dragging, and crushing bone.

F. Smaller tooth in mandible
Here is a slightly smaller tooth in the lower jaw, tooth #17. It is also very strongly built, only about twice as tall as it is wide across its base. Notice that it has a little more of a curve than the large tooth and comes to a more slender tip. This tooth-- there are about 30 in a row like it above and below--make sure that nothing escapes the enormous jaws of the predator.

Skull Stats
Length of adult skull: 6 feet
Number of bones in skull: about 50 in the cranium (upper part) and
12 in the mandible (6 each side)
Number of teeth: 132
Most fragile bone: ear bone (stapes)

Questions
If the scale bar in F is 1/4", how tall is tooth 17t?