Mosasaurs

Mosasaurs were fearsome sea reptiles that ruled the oceans. They lived during the last 20 million years of the Cretaceous Period. They were not dinosaurs but giant marine lizards. Mosasaurs were related to modern monitor lizards and snakes!

Ocean Giants

The biggest mosasaurs were over 50 feet long. That is about as long as a school bus! They had long, powerful bodies and strong tails for swimming fast. Their jaws were filled with sharp, cone-shaped teeth. Some mosasaurs had a second row of teeth on the roof of their mouth.

Top of the Food Chain

Mosasaurs ate almost anything in the ocean. They hunted fish, sharks, sea turtles, and even other mosasaurs! They could open their jaws very wide, similar to how snakes do. Mosasaurs breathed air and had to come to the surface regularly. They went extinct along with the dinosaurs.

Fun Facts

• Mosasaur jaws could flex open like a snake's to swallow large prey.
• The first mosasaur fossil was found in a limestone quarry in the Netherlands in 1764.
• Some mosasaurs had flippers with tiny fingers inside, showing they evolved from land animals.

Did You Know?

Mosasaurs are actually more closely related to today's Komodo dragons than to dinosaurs. They evolved from small land lizards that slowly adapted to life in the ocean!