During the 200 million years that dinosaurs roamed the land, the oceans were ruled by formerly land-dwelling reptiles. Of these, ichthyosaurs adopted dolphin-like forms, plesiosaurs became sea lion-like, and mosasaurs occupied crocodile-like ‘ambush’ predator roles.
Although this is intended as a light-hearted guide to areas of science that might interest you, it serves to illustrate the inter-disciplinary nature of science.