At the same time T-Rex was roaming the land, the giant mosasaur Prognathodon was the top predator in the sea, preying on everything from turtles to sharks.

These terrifying creatures could grow up to 60 feet (18 metres) long, weighing as much as 20 tons and would have spent most of the day swimming near the seabed stalking their next meal. Even though these amazing animals lived at the time of the dinosaurs, they are members of the Order Squamata, meaning they are very closely related to modern snakes and lizards.

Prognathodon, and the mosasaurs, were the most advanced hunters to ever roam the sea. They had a combination of special adaptations for hunting and killing prey that are only seen in other hunters in isolation.

Large Eye Opening

Prognathodon had a large variety of tools to sense prey. They had very large eyes in relationship to the skull, which would allow them to see well in low light. They also possessed a third eye on top of their skull. This was not an eye like one might initially think, but was a light sensing organ which would allow Prognathodon to sit silently on the sea floor and sense changes in light as prey swam overhead. This same feature is seen only in a few modern monitor lizards.

Light-sensing Eye

Prognathodon also had what appears to be Jacobson’s Organs very similar to those used by modern snakes to smell prey. This would allow Prognathodon to flick its tongue in the water and smell its prey from great distances.

Top View of Possible Jacobson’s Organs

Prognathodon also had a large number of pits around the upper and lower jaws and on the end of their snout. Most scientists believe that these were similar to those in sharks, called the Ampullae of Lorenzini. These organs sense the faint electrical impulses of their prey and allow them to zero in in even zero light conditions.

Pits in Prognathodon Snout

After Prognathodon had prey in its mouth, it had an arsenal of weapons that made sure it would not leave. Perhaps the most bizarre and incredible is a second set of teeth set back in the throat called pterygoids. These teeth were attached to muscles and operated independently of its jaws. This means they could reach forward and pull prey back, while maintaining a grip with the jaws themselves. Modern Pythons and Anacondas have similar sets of second teeth that also move independently to march the snakes head over their prey.

Modern Python Pterygoids

Mosasaur Pterygoids

Prognathodon, as well as most mosasaurs had two sets of hinges on their lower jaws. The front hinge was connected by a very elastic tissue, which would allow them to open their mouths incredibly wide. It is also believed by many scientists that lower jaws were not connected so they could expand their mouths to accommodate very large prey, much like modern snakes.

Two Sets of Hinges

Given all of these advanced features, it is easy to see why Prognathodon was truly the king of the sea.

Seth Sorensen
Fossil Shack