First, there were dinosaurs. Then came mammals.
Many people believe that mammals never co-existed with dinosaurs and evolved after the non-avian dinosaurs went extinct 65 million years ago.
But they sure did!
During the Mesozoic Era, while dinosaurs were the rulers of the earth, many species of small, rodent-like mammals were scurrying around underfoot, having established their own ecological niche over 200 million years ago.