As an educator at the American Museum of Natural History, I knew enough about paleontology to tell people that there were no known aquatic dinosaurs. To many peoples’ surprise plesiosaurs, icthyosaurs, mosasaurs (and all the other fossil marine reptiles so often depicted in books and TV shows) – none of them were actually dinosaurs. They were very different types of reptiles, extinct sauropterygians and icthyopterygians (mosasaurs were actually a kind of lizard) that lived in the seas during the Mesozoic Era while dinosaurs ruled the land.
Jurassic Park 3 came out in 2001, which featured a Spinosaurus that swam like a crocodile, and all the people were like, “See! Dinosaurs COULD swim!” But I never said dinosaurs couldn’t swim. There has long been fossil evidence – in the form of trackways that resemble scraped claws against river floors – that dinosaurs probably were pretty good swimmers, and waterways wouldn’t have presented much of a dispersal barrier, just like caribou and other large modern migrating animals who eventually encounter water at some point in their life and have to cross it. Still, there were no fossil remains ever described as belonging to a dinosaur that actually lived in the water.
Since it’s discovery over 100 years ago, Spinosaurus has been known as one of the largest theropods. Theropods are a large group of dinosaurs which includes not only all birds but all the familiar carnivorous species, including Allosaurus and Velociraptor. Spinosaurus was bigger than even the biggest Tyrannosaurus. This week, the journal Science published the paper “Semiaquatic Adaptations in a Giant Predatory Dinosaur“, in which a group of scientists make the case for a long list of adaptations supporting the idea that this huge meat-eating dinosaur with a sail on its back was also well adapted to life in the water.
Finally, a dinosaur that lived in the water and swam and ate fish like a crocodile. I have been waiting my whole life for there to be one, and here it was under our noses the whole time. Good ol’ Spinosaurus. Museum educators will have to adjust their curriculum accordingly.