RHAMPHORHYNCHOIDS JURASSIC WELL LONG TAIL WITHOUT SMALL [Illustration] DEVELOPED WITH CREST MAXIMUM _RHAMPHORHYNCHUS_ FLATTENED WINGSPAN RUDDER AT OF 2 FEET END PTERODACTYLOIDS JURASSIC JAW PARTLY SHORT OR WITH SMALL FROM SIZE [Illustration] AND OR NO TAIL OR LARGE OF _PTERANODON-K_ CRETACEOUS COMPLETELY CREST SPARROW TOOTHLESS, TO GIANTS HORNEY BEAK WITH SPAN OF 25′ [Illustration: MESOZOIC SWIMMING REPTILES] GROUP AGE DESCRIPTION SIZE HABITAT EXAMPLE ICHTHYOSAUR TRIASSIC FISH-LIKE BODY, AVERAGE MARINE [Illustration] TO HEAD LONG AND LENGTH = _ICHTHYOSAURUS-J_ CRETACEOUS POINTED, NO 7′ DISTINCT NECK MAXIMUM LENGTH = 43′ MOSASAUR CRETACEOUS LIZARD-LIKE AVERAGE MARINE [Illustration] BODY, FLATTENED LENGTH = _PYLOSAURUS_ TAIL, 15′-20′ DOUBLE-JOINTED MAXIMUM JAW, RECURVED LENGTH = TEETH 50′ PLESIOSAUR TRIASSIC LONG NECK AND MAXIMUM MARINE [Illustration] TO SMALL HEAD OR LENGTH = _ELASMOSAURUS-K_ CRETACEOUS LONG HEAD AND 50′ _TRINACROMERUM-K_ SHORT NECK, POWERFUL FLIPPERS CHELONIA TRIASSIC SHAPED LIKE MAXIMUM MARINE, [Illustration] (TURTLES) TO PRESENT MODERN TURTLES, SIZE = STREAMS, _ARCHELON-K_ BODY COVERED 11′ × 12′ AND WITH BONY PLATES TERRESTRIAL PHYTOSAUR TRIASSIC CROCODILE-LIKE MAXIMUM STREAMS [Illustration] BODY, NOSTRILS LENGTH = AND SWAMPS _RUTIODON_ ON A “HUMP” 25′ ALMOST BETWEEN THE EYES [Illustration: Plate 40] PELYCOSAUR × ¹/₁₂ DIMETRODON PRIMITIVE AMPHIBIAN × ¹/₂₀ ERYOPS COTYLOSAUR SEYMOURIA × ⅕ [Illustration: Plate 41 SWIMMING REPTILES]