Spinosaurus has a giant tail fin! And, it used it to swim! Long awaited paper published today in Nature describes new fossil material that shows the tail of the large-bodied theropod Spinosaurus was dorsoventrally expanded into a paddle-like appendage. Working in collaboration with Nizar Ibrahim - spinosaur extraordinaire - Stephanie and MCZ colleague George Lauder use biorobotics to show that the tail of Spinosaurus could produce forward thrust more similar to modern aquatic tetrapods (e.g. crocodiles and salamanders) than other dinosaurs. Implication: dinosaurs invaded the aquatic realm!
Ibrahim, N., Maganuco, S., Dal Sasso, C. et al...Pierce SE. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 581, 67–70 (2020).