Great white, bull and tiger sharks are some of today’s most talked-about sharks. But have you met the sharks of yesterday? Each prehistoric shark had its own amazing - and sometimes strange - features. The scissor-tooth shark had teeth in a spiral shape. The giant megalodon was about three times the size of a great white. One small prehistoric shark had a big dorsal fin in the shape of an ironing board! Readers will gobble up all the facts about these early ocean hunters and learn how they compare to modern sharks. Part of the Sharks Close-Up series.