We talk a lot about the aquatic nature of Spinosaurus well here is a dinosaur whose streamlined body is a major adaptation for aquatic animals to move efficiently in the water. Natovenator polydontus from the Upper Cretaceous of Mongolia.
https://www.nature.com/articles/s42003-022-04119-9
https://www.smithsonianmag.com/science-nature/worlds-first-swimming-dinosaur-discovered-in-mongolia-180981217/#.Y4jcTsmaCbk.twitter