AMNIOTA Lepidosauria Plesiosauria Mammalia Placodontia Testudines Sauropterygia Thrinaxodon Archosauria Ichthyosauria Archosauriformes Pareiasauria Euryapsida Dicynodontia Archosauromorpha Petrolacosaurus Therapsida Enlarged ITF Incisors canines cheek teeth Forelimbs more developed than hind Synapsida Infratemporal fenestra Amphibia Euparkeria Antorbital and mandibular fenestrae air sac system Bellybreathing Sauria Mesosaurus Dimetrodon Diapsida Infra and Supratemporal fenestrae Hindlimbs more powerful than forelimbs Parareptilia Reptilia Aglandular skin Water conserving kidneys enhanced color vision AMNIOTA Amniotic egg Claws Live on land for entire life cycle Tetrapoda Limbs with digits Necks Live on land as adults ARCHOSAURIA Marasuchus Crocodylomorpha Rauisuchoidea Dinosauria Loricata Poposauroidea Paracrocodylomorpha Silesauridae Pterosauria Aetosauria Elongate pubes and ischia Lagerpetidae Dinosauriformes Suchia Phytosauria Scleromochlus Crurotarsi Dinosauromorpha Parasagittal stance hinge like ankle joint Ornithodira Neck with S shaped curve Avemetatarsalia Elongate tibiae and metatarsi loss of body armor Euparkeria ARCHOSAURIA Nests with vegetation Parental care of young parasagittal stance one way flow through lungs Archosauriformes Antorbital and mandibular fenestrae air sac system Belly breathing DINOSAURIA Sauropodomorpha Marginocephalia Theropoda Ornithopoda Saurischia Thyreophora Ornithischia DINOSAURIA Silesauridae Semiopposable Manual Digit I Reduced Manual Digits IV V Open perforate Acetabulum ORNITHISCHIA Marginocephalia Ornithopoda Thyreophora Neornithischia Asymmetrical enamel on teeth Heterodontosauridae Genasauria Eocursor Deep powerful skulls Premaxillary tooth row ventral to maxillary tooth row Jaw joint ventral to dentary tooth row Hands reduced in size and reduced grasping ability Pisanosaurus Backwards pointing Pubis Epaxial ossified tendons Inset tooth row for cheeks ORNITHISCHIA Broad Leaf shaped Teeth with Large Denticles Predentary Bone 5 or more sacrals Dinosauria Saurischia THYREOPHORA Edmontonia Stegosaurinae Euoplocephalus Sauropelta Dacentrurinae Gastonia Short triangular head Triangular hornlets on skull Complex nasal chambers Tail club Ankylosauridae Stegosaurinae Pinacosaurus Nodosauridae Huayangosauridae Paired plates and spikes Thagomizer Ankylosauria Osteoderms fused to skull Rings of osteoderms on neck and shoulder Extensive osteoderms over body Wide across body Stegosauria Scelidosaurus Eurypoda Scutellosaurus Larger size Heavier armor Obligate quadrupedality Neornithischia THYREOPHORA Osteoderms Ornithischia ORNITHOPODA Styracosterna Greatly enlarged nares much larger size Spike thumb metacarpals II IV hoof like metacarpal V opposable Dryosauridae Camptosaurus Tenontosaurus Ankylopollexia Well developed pleurokinetic hinge Rhabdodontidae Dryomorpha Iguanodontia Hypsilophodontidae Thescelosauridae Larger size Premaxilla toothless Enlarged naris 6 or more sacrals ORNITHOPODA Premaxillary lower margin ventral to maxillary tooth row Mandibular articulation ventral to dentary tooth row Pleurokinetic hinge joint in cranium Marginocephalia Othnielosaurus Genasauria Neornithischia STYRACOSTERNA Anatotitan Gryposaurus Parasaurolophus Corythosaurus Saurolophinae Extremely enlarged nares Greatly flared snout Hadrosauridae Lambeosaurinae Protohadros Hollow nasal chamber forming crest on top of head End of premaxillae flare outwards duckbill Increased number of teeth Dental battery Manual digit I lost Metacarpals II IV greatly elongated Hadrosauria Ouranosaurus STYRACOSTERNA Greatly enlarged nares much larger size Spike thumb Metacarpals II IV hoof like Metacarpal V opposable Ankylopollexia Iguanodon Camptosauridae MARGINOCEPHALIA Zuniceratops Ceratopsidae Leptoceratopsidae Even larger size Nasal horn Shearing dental battery Ceratopsoidea Protoceratopsidae Psittacosauridae Larger size Postorbital horns Coronosauria Enlarged frill Enlarged skull Obligate quadrupedality Archaeoceratops Pachycephalosaurus Neoceratopsia Frill Stegoceras Dome Pachycephalosauria Quadrupedality Thickened skull roof Small ossifications along ridge of skull Ceratopsia Rostral bone Jugals form pointed horns MARGINOCEPHALIA Ornithopoda Shelf of bone extending back over occipital region of skull Genasauria CERATOPSIDAE Triceratops Styracosaurus Anchiceratops Centrosaurus Chasmosaurinae Nasal horns enlarged postorbital horns reduced Albertaceratops Longer shallower snouts Elongated rostral Long frills Centrosaurinae Short deep snout pair of spikes projecting from back of frill CERATOPSIDAE Even larger size Nasal horn Shearing dental battery Zuniceratops Ceratopsoidea Larger size Postorbital horns SAURISCHIA basal theropods Tawa Neotheropoda Eodromaeus Premaxilla maxilla kink Sauropodomorpha Herrerasauria Theropoda Blade like serrated teeth Promaxillary fenestra Intramandibular joint Enlarged hands with increased grasping ability SAURISCHIA Ornithischia Special Articulations hyposphene hypantrum in dorsal vertebrae Elongated Neck Hollow air sac chambers in cervicals Metacarpal I reduced Enlarged thumb claw Manual Digit II longest in the manus Dinosauria SAUROPODOMORPHA Cetiosauridae Antetonitrus Neosauropoda core prosauropods Mamenchisauridae Melanorosauridae Teeth at front of snout Nares dorsally placed Columnar metacarpus Eusauropoda Shunosaurus Plateosauridae Vulcanodontidae basal sauropodomorphs Frurther size increase 12 or more cervicals Modified manus and pedes Rounded snout tooth to tooth occlusion wide gape loss of cheeks Sauropoda Shortened snout obligate quadrupeality Riojasauridae Quadrupeality Massospondylidae Anchisauria Guaibasauridae Further size increase some quadrupeality Massopoda Plateosauria Efraasia Increased body size even longer neck shortened distal hindlimb Cheeks SAUROPODOMORPHA Decreased skull size tall leaf shaped teeth long neck possible small beak on dentary Saurischia Theropoda NEOSAUROPODA Diplodocidae Antarctosauridae Lithostrotia Brachiosauridae Lognkosauria Reduced size Osteoderms Extremely elongate necks and tails Dicraeosauridae Eutitanosauria Pencil shaped teeth Six sacral vertebrae Reduced manual digits Titanosauria Extra wide pelves More flexible dorsals Robust radii ulnae Forelimbs longer than hindlimbs Elongated Rebbachisauridae necks Astrodon Titanosauriformes Camarasaurus Expanded snout Nares on top of skull Gnawing dental battery Flagellicaudata Nares joined together above orbit Long skulls Short forelimbs Whip tail Diplodocoidea