Think of the Jurassic and the first type of animal that comes to mind would be a dinosaur. It might be green, maybe it has feathers, but it almost certainly would be big. However, mammal fossil finds over the last 20 years and new research on how fast these extinct animals diversified shows that Jurassic mammals were equally spectacular. From the gliding Volaticotherium to the aquatic Castorcauda, mammals were not background animals in a dinosaur dominated scene.