Class Blastoidea 81 Class Crinoidea 81 Subphylum Eleutherozoa 82 Class Asterozoa 82 Subclass Asteroidea 82 Subclass Ophiuroidea 82 Class Echinozoa 82 Subclass Echinoidea 82 Subclass Holothuroidea 85 Phylum Chordata 85 Subphylum Hemichordata 85 Class Graptolithina 85 Subphylum Vertebrata 86 Superclass Pisces 87 Class Agnatha 87 Class Placodermi 87 Class Chondrichthyes 87 Class Osteichthyes 87 Superclass Tetrapoda 89 Class Amphibia 89 Class Reptilia 89 Cotylosaurs 89 Turtles 89 Pelycosaurs 89 Therapsids 89 Ichthyosaurs 95 Mosasaurs 95 Plesiosaurs 95 Phytosaurs 95 Crocodiles and alligators 95 Pterosaurs 95 Dinosaurs 95 Order Saurischia 97 Suborder Theropoda 97 Suborder Sauropoda 97 Order Ornithischia 97 Suborder Ornithopoda 97 Suborder Stegosauria 97 Suborder Ankylosauria 97 Suborder Ceratopsia 100 Class Aves 100 Class Mammalia 100 Subclass Allotheria 100