They were larger than life-their world and physiology so alien as to be almost unimaginable. For millions of years they swam the seas soared across the skies and ruled the earth. In this exciting feature-length special PREHISTORIC MONSTERS REVEALED puts the flesh back on the bones of some of the most lethal terrifying and bizarre creatures that ever roamed the planet. From humongous armored sharks to fierce fighting birds to mammals built like tanks get a rare insight into what these animals looked like how they lived and how they met their ultimate demise. Find out how they became precisely adapted to survive and thrive in their environment and learn why creatures of their massive size do not exist today. Featuring the latest science and technology and captivating interviews with leading experts HISTORY presents the most revealing portrait of these animals ever seen.