marine reptiles that lived in most of the world's oceans and shallow seas during the late Cretaceous Period, 70-65 million years ago

The name "mosasaur" means "Meuse Reptile," which refers to the fact that the first named specimen was found near the Meuse River in the Netherlands. It is believed that mosasaurs were distant ancestors of the monitor lizards (such as the Komodo dragon) of today.

The smallest mosasaurs were about 12-15 feet long and weighed a few hundred pounds, while the largest were 50+ feet long and weighed over 15 tons. All mosasaurs, however, had large heads, powerful jaws, streamlined bodies, and two sets of flippers (modified limbs). They likely used a sinuous, undulating movement of the tail to propel self themelves rapidly, much like modern sea snakes and swimming alligators. Like modern marine reptiles, mosasaurs had to surface to breathe. Unlike most of their descendants, however, which lay eggs on land, mosasaurs gave birth to live young in the water, and there is some evidence to suggest at least some degree of parental care for young.

All mosasaurs were carnivorous, and it is likely that the larger species were at the top of the food chain. Prey varied depending on size, but fish, squid, ammonites, turtles, small plesiosaurs, and even other mosasaurs were on the menu.

The first mosasaur fossil was discovered near the town of Maastricht, Netherlands, between 1770 and 1774. The fossil was initially studied by Dr. C.K. Hoffman, who believed it to be a giant crocodile. It was subsequently studied by naturalist Georges Cuvier, who was the first to determine that the skeleton belonged to an extinct animal, and he named it Mosasaurus hoffmanni. Since then, mosasaur fossils have been discovered throughout much of the United States and Canada, South America, northern Europe, Africa, the Middle East, Australia and New Zealand, and on a few islands off the coast of Antarctica.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Reptilia
order Squamata
family Mosasauridae
Clidastes propython
Dallasaurus
Eonatator
Globidens
Hainosaurus
Halisaurus
Mosasaurus hoffmanni
Mosasaurus maximus
Platecarpus tympaniticus
Plioplatecarpus
Plotosaurus
Prognathodon
Tyloasaurus proriger

SEE ALSO
Georges Cuvier

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This page was last updated on 06/27/2017.