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.