Prehistoric marine animals. Artwork showing the outlines of various living and extinct marine animals compared to a human. From top to bottom (and from left to right): blue whale (30 metres), Leedsichthys (27 metres), Shonisaurus (21 metres), Megalodon (20 metres), Kronosaurus (10 metres), Liopleurodon (10 metres), Tylosaurus (15 metres), Dunkleosteus (10 metres), Styxosaurus (12 metres), Xiphactinus (5 metres), Archelon (4 metres) and a human diver (1.8 metres).