Definition of mosasaur in English:



(also mosasaurus)
  • A large extinct marine reptile of the late Cretaceous period, with large toothed jaws, paddle-like limbs, and a long flattened tail, related to the monitor lizards.

    Family Mosasauridae, suborder Lacertilia: several genera, including Mosasaurus

    ‘The remains include the bones of dinosaurs, birds, and large marine reptiles such as mosasaurs and elasmosaurs, as well as fossilized sponges, mollusks, pine cones, and diverse fish teeth.’
    • ‘The dinosaurs were only one of the groups that became extinct at the end of the Cretaceous; also hard-hit were the unicellular Foraminifera, the ammonites, and marine reptiles such as the mosasaurs and plesiosaurs.’
    • ‘Today paleontologists know the Badlands are full of bones of mosasaurs (giant marine reptiles that plied an inland sea there during the Cretaceous period) and pterosaurs (giant flying reptiles).’
    • ‘Contemporaries of the last dinosaurs, paddle-limbed mosasaurs, inhabited seas of the Cretaceous period, which ended about 66 million years ago.’
    • ‘It represents a remarkable find because partial skeletons of mosasaurs from the Late Cretaceous marine strata exposed along the Atlantic coast from New Jersey to the Carolinas are rare.’
    • ‘But proponents of a watery origin believe that snakes most likely evolved from extinct marine reptiles called mosasaurs, powerful swimmers that spent their entire lives in the ocean.’
    • ‘In the Mesozoic top predators included the biggest theropod dinosaurs on land, and pliosaurs and mosasaurs in the seas.’
    • ‘The group also includes a number of animals that have returned to life in the water, such as sea turtles, sea snakes, whales and dolphins, seals and sea lions, and extinct groups such as plesiosaurs, ichthyosaurs, and mosasaurs.’
    • ‘The locality and dimensions of the South Dakota ‘fish’ have led paleontologists to guess that the creature was a long-necked plesiosaur or a serpentine mosasaur.’
    • ‘Because the Kansas chalk seemed to be devoid of juvenile mosasaurs, paleontologists early in the 20th century proposed that the reptiles either laid eggs on land or gave birth to their young near the shore to protect them from predators.’
    • ‘A new fossil mosasaur, one of a group of non-dinosaurian reptiles that return to marine existence, has been found by an amateur fossil hunter.’
    • ‘One reptile was the mosasaur, a giant snake-like reptile that measured up to 18 m.’
    • ‘His team found compelling evidence that in fact these snakes are a side-branch of snake evolution, closely related to modern boas and pythons and not mosasaurs.’
    • ‘When snakes first appeared, the only seagoing lizards were giant mosasaurs.’
    • ‘During their comparatively brief geological lifespan mosasaurs were nonetheless very successful, and following their first appearance in the Turonian they rapidly became abundant in epicontinental seas worldwide.’
    • ‘Unfortunately, these descriptions are too generalized and/or lack accompanying illustrations, and hence cannot be used to separate Halisaurus from other mosasaurs.’
    • ‘As in mosasaurs, the mechanics of egg-laying (if any) and prenatal care (if any) are not easy to imagine.’
    • ‘Some evolutionists claim that snakes came out of the sea, from something like a mosasaur.’
    • ‘The majority of these records are from the USA, where Late Cretaceous strata of the Western Interior, the Gulf Coast, and the Eastern Coastal Plain provide a nearly continuous sequence of mosasaur faunal evolution.’



/ˈmōsəˌsôr/ /ˈmoʊsəˌsɔr/


Mid 19th century from modern Latin Mosasaurus, from Latin Mosa, ‘Meuse’ (the river near which it was first discovered) + Greek sauros ‘lizard’.