CLEP Social Sciences

Answer - B - Dinosaurs roamed the Earth during the Mesozoic era.

Key Takeaway: The Mesozoic Era, which is part of the Phanerozoic Eon, began about 248 million years ago and is commonly known as the Age of Reptiles. During this era, large reptiles, such as dinosaurs, dominated the land. The end of the era saw the largest mass extinction in the history of the Earth. Some scientists have estimated that up to 90 percent of the species alive during this era became extinct. Although the reason for this is not fully known, it is often believed that climate change caused the extinction.