Carcharodon megalodon (aka Carcharocles megalodon) was THE apex predator of the oceans during the Miocene and Pliocene geological periods.  Experts differ on the correct classification for these sharks (as evidenced by two accepted names).  Also, disagreements exist as to the maximum size of these animals, ranging from about 50ft in length to as much as 90ft.  Maximum body mass (weight) estimates range as high as 100,000+lbs.  Extinct sharks are quite difficult to study, as the cartilaginous skeleton is rarely fossilized.  These teeth were recovered by divers off the east coast of the United States.  Measurements are maximum diagonal measure of long side x diagonal measure of short side x maximum width.