Despite not being particularly mammal-looking, the earliest true mammals began to rise about 200 million years ago, when dinosaurs were still roaming Earth. However, the therapsids still had ...

Before dinosaurs walked the Earth and tens of millions of years before the first mammals appeared, distant mammal relatives with long, serrated canine teeth were the dominant carnivores on land.

This cartilage eventually became further elaborated to form the prominent outer ears of early mammals. An additional surprise was that the elastic cartilage of gills may have arisen much earlier ...