First and most importantly, mosasaurs are not dinosaurs. They are extinct marine reptiles that are believed to be distantly related to monitor lizards such as the Komodo Dragon. More recent evidence, however says they were even more closely related to snakes than monitor lizards. These large reptiles often reached lengths of 30 to 40 feet. Many complete mosasaur specimens have been found in the Niobrara Formation of Western Kansas, and some of the first mosasaur remains were collected more than 130 years ago. As a group, the fossilized remains of mosasaurs had been found all over the world, from Kansas to the Dakotas and Montana. They are also found most other states and in Canada. Overseas, mosasaurs are found in northern Europe, to Turkey, Israel to Africa, and from Brazil to Peru. And they’re found in Australia and New Zealand to the islands off the coast of Antarctica.