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.
User: During which period did mammals first appear? a. Pleistocene b. Carboniferous c. Cretaceous d. JurassicWeegy: Mammals first appeared during Jurassic period. Expert answered|jin_jae_min|Points 408|User: Biomes on Earth have exhibited changes throughout history that have been caused by a variety of factors.