Mosasaurus and other mosasaurs ruled the seas for millions of years.
Mosasaurus was a ferocious predator in the ancient oceans of the Cretaceous period (145.5 million to 65.5 million years ago). While dinosaurs dominated the land, Mosasaurus used its long tail and stumpy, paddle-like limbs to cruise through the water, devouring all kinds of prey with its massive jaws and sharp, cone-shaped teeth.
Mosasaurus is one genus, or group of species, out of dozens that made up a diverse family of marine reptiles called mosasaurs. The mosasaurs ruled the ocean in the late Cretaceous period. They were not sea dinosaurs, but a separate group of reptiles, more closely related to modern snakes and lizards, according to the Philip J. Currie Dinosaur Museum.
Mosasaurs went extinct 65.5 million years ago in the same mass extinction event that wiped out the dinosaurs, Live Science previously reported. A Mosasaurus species has since been fictionally resurrected on the big screen, most notably in the 2015 movie blockbuster “Jurassic World,” increasing the profile of this mighty group of marine reptiles.
Mosasaurus species are among the largest members of the mosasaur family, according to the Philip J. Currie Dinosaur Museum. One of the biggest specimens ever found was identified as Mosasaurus hoffmanni and was estimated to be about 56 feet (17 meters) long in life, according to a 2014 study published in the journal Proceedings of the Zoological Institute RAS. Not all mosasaurs were giants though. Some species, such as Xenodens calminechari, were only about the size of a porpoise.
The biggest Mosasaurus would have been comparable in size to the mighty megalodon — a giant shark that dominated oceans in the middle Miocene and Pliocene epochs (15.9 million to 2.6 million years ago), long after the mosasaurs went extinct 65.5 million years ago. Megalodons could have reached up to 49 to 59 feet (15 to 18 meters) long, according to the Natural History Museum (NHM) in London. Neither of these predators, however, were ever as big as the modern blue whale, which can reach up to 110 feet (34 meters) long and is the biggest known animal to have ever existed.
Mosasaurs were the ocean’s most dominant predator at the end of the Cretaceous period and lived across the world’s oceans. Large mosasaurs would have likely eaten almost any kind of prey they were able to catch, including fish, sharks, sea birds and even other mosasaurs, according to the U.S. National Park Service. These mosasaurs were apex predators and could be compared to modern orcas, while other mosasaur species were more specialized feeders and adapted to eat shellfish, like modern sea otters.