Medical dictionary definition of AF as a medical term including diseases, symptoms, treatments, and other medical and health issues. About Us Bookmark this page
Dinosaurs lived between 230 and 65 million years ago, in a time known as the Mesozoic Era. This was many millions of years before the first modern humans, Homo sapiens, appeared. Scientists divide the Mesozoic Era into three periods: the Triassic, Jurassic and Cretaceous.inosaurs lived between 230 and 65 million years ago, in a time known as the Mesozoic Era. This was many millions of years before the first modern humans, Homo sapiens, appeared. Scientists divide the Mesozoic Era into three periods: the Triassic, Jurassic and Cretaceous.
Ask the average person (or high-schooler) on the street, and theyâll guess that the first mammals didn't appear on the scene until after the dinosaurs went extinct 65 million years ago--and that the last dinosaurs evolved into the first mammals.