Mosasaurs were large marine reptiles which ruled the sea during the era of dinosaurs and became extinct about 65 million years ago. They could grow up to a length of 50 feet and gave birth to live offspring at sea, as per a new study. Specimens of young mosasaurs have been identified recently at the Yale Peabody of Museum of Natural History by the researchers from Yale University and the University of Toronto. The fossils were originally misidentified as birds. However, now their proper identification has unveiled several details about the legendary aquatic predators. The study has appeared in the journal Palaeontology.
Daniel Field, lead author of a study and a doctoral candidate in the lab of Jacques Gauthier in Yale’s Department of Geology and Geophysics stated “Mosasaurs are among the best-studied groups of Mesozoic vertebrate animals, but evidence regarding how they were born and what baby mosasaur ecology was like has historically been elusive.” Field and his fellow researchers have described the youngest mosasaurs found to date. Field commented “These specimens were collected over 100 years ago. They had previously been thought to belong to ancient marine birds.”
Field and University of Toronto at Mississauga doctoral candidate Aaron LeBlanc have identified a variety of tooth and jaw features in the remains which represent mosasaurs. Moreover, all the fossils were found in ocean deposits. LeBlanc mentioned “Really, the only bird-like feature of the specimens is their small size. Contrary to classic theories, these findings suggest that mosasaurs did not lay eggs on beaches and that newborn mosasaurs likely did not live in sheltered nearshore nurseries.”
Researchers rarely get the opportunity to know more about things like birth in a long extinct aquatic species. Field said “Coming across these tiny mosasaur specimens was really serendipitous. It’s not every day that you’re able to shed new light on the biology of animals that went extinct 65 million years ago.” The study reveals that the mosasaur was an unusual reptile.
Modern reptiles and fish lay eggs for reproduction. Even sea turtles reproduce by laying eggs for which they come ashore. Only aquatic mammals like dolphins and whales are known to give birth to live offspring at sea. During the cretaceous period sea levels were quite high due to which many of the reptiles moved into the warm oceans. Mosasaur remains have been found in almost all parts of Europe, North America, South America, Australia, New Zealand and Antarctica.