Geology of the Mesozoic Era

Tylosaurus of the Niobrara Chalk

TylosaurusCarnegie Museum's Tylosaurus specimen is a cast of a specimen recovered from Niobrara chalk deposits. Tylosaurus is not actually a dinosaur, but a large carnivorous marine reptile belonging to the group known as Mosasaurs. It swam in the Late Cretaceous seas that extended across much of the western United States.

The chalk deposits in which Tylosaurus was found are made up of microscopic organisms known as coccoliths, the disarticulated remains of a marine plankton (coccolithophorids). This is what the Cretaceous chalk sea floor might have looked like during the Late Cretaceous.

Niobrara Sea Floor
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