Gliding Jurassic mammals, huge dinosaurs and ice age birds

The mammals that lived in the shadows of the dinosaurs were always depicted as small, shrew-like beasts. We now have clear evidence that early mammals had diversified into a number of specialised niches, such as aquatic forms like the beaverine Castrocauda from the Jurassic of Mongolia, and large predatory forms like Repanomamus from the Cretaceous.