Ohmdenosaurus Pectinodon - dubious troodontidae Ojoceratops - possible junior synonym of Eotriceratops Pedopenna Ojoraptorsaurus Pegomastax Oligosaurus – junior synonym of Rhabdodon Peishansaurus - nomen dubium Olorotitan Pekinosaurus – a pseudosuchian; possibly a junior synonym of Revueltosaurus Omeisaurus Pelecanimimus "Omosaurus" – preoccupied name, now known as Dacentrurus Pellegrinisaurus Onychosaurus – possible synonym of Rhabdodon, or a dubious ankylosaurian Peloroplites Oohkotokia Pelorosaurus Opisthocoelicaudia – possible junior synonym of Nemegtosaurus "Peltosaurus" – preoccupied name, now known as Sauropelta Oplosaurus - dubious Macronaria Penelopognathus "Orcomimus" – nomen nudum Pentaceratops Orinosaurus – junior synonym (unneeded replacement name) of Orosaurus Petrobrasaurus Orkoraptor Phaedrolosaurus - nomen dubium Ornatotholus – junior synonym of Stegoceras Philovenator Ornithodesmus - dromaeosauridae indet. Phuwiangosaurus "Ornithoides" – nomen nudum; Saurornithoides Phyllodon Ornitholestes Piatnitzkysaurus Ornithomerus – junior synonym of Rhabdodon Picrodon - non-dinosaurin archosaur, now known as Avalonianus Ornithomimoides - dubious theropod Pilmatueia Ornithomimus Pinacosaurus Ornithopsis - dubious titanosauriformes Pisanosaurus - possibly a silesaurid Ornithosuchus – a non-dinosaurian archosaur Pitekunsaurus Ornithotarsus – junior synonym of Hadrosaurus Piveteausaurus Orodromeus Planicoxa Orosaurus – junior synonym of Euskelosaurus Plateosauravus Orthogoniosaurus - dubious ceratosaurian Plateosaurus Orthomerus Platyceratops - possible Bagaceratops Oryctodromeus Platypelta "Oshanosaurus" – nomen nudum Plesiohadros Osmakasaurus Pleurocoelus – possible junior synonym of Astrodon Ostafrikasaurus Pleuropeltus – junior synonym of Struthiosaurus Ostromia Pneumatoarthrus – a turtle Othnielia - dubious ornithischian Pneumatoraptor - Indeterminate Paraves Othnielosaurus – possible junior synonym of nanosaurus Podokesaurus Otogosaurus Poekilopleuron Ouranosaurus Polacanthoides – junior synonym of Hylaeosaurus Overosaurus Polacanthus Oviraptor Polyodontosaurus - nomen dubium "Ovoraptor" – nomen nudum; Velociraptor Polyonax - dubious ceratopsidae Owenodon Ponerosteus - a non-dinosaurian archosaur Oxalaia Poposaurus – a non-dinosaurian archosaur Ozraptor Postosuchus – a rauisuchian Powellvenator Pachycephalosaurus Pradhania Pachyrhinosaurus Prenocephale Pachysauriscus – junior synonym of Plateosaurus Prenoceratops Pachysaurops – junior synonym of Plateosaurus Priconodon - dubious nodosauridae "Pachysaurus" – preoccup. name, now Pachysauriscus; junior syn. of Plateosaurus Priodontognathus - dubious Ankylosauria Pachyspondylus – probable junior synonym of Massospondylus Proa Pachysuchus - nomen dubium Probactrosaurus Padillasaurus Probrachylophosaurus Pakisaurus - invalid taxa Proceratops – junior synonym (unneeded replacement name) of Ceratops Palaeoctonus – a phytosaur Proceratosaurus Palaeocursornis – an azhdarchoid pterosaur Procerosaurus – a prolacertiform archosauromorph, Tanystropheus "Palaeolimnornis" – nomen nudum; Palaeocursornis, pterodactyloid pterosaur "Procerosaurus" – preoccupied name, now known as Ponerosteus Palaeopteryx – possibly a bird Procheneosaurus – junior synonym of Lambeosaurus Palaeosauriscus – junior synonym of Paleosaurus Procompsognathus "Palaeosaurus" – preoccupied name, now known as Paleosaurus Prodeinodon - dubious theropod "Palaeosaurus" – preoccup. name, now Sphenosaurus, a procolophonid "Proiguanodon" – nomen nudum; Iguanodon Palaeoscincus - dubious ankylosaurian Propanoplosaurus Paleosaurus – a non-dinosaurian archosaur Proplanicoxa – probable junior synonym of Mantellisaurus Paludititan Prosaurolophus Paluxysaurus – junior synonym of Sauroposeidon Protarchaeopteryx Pampadromaeus Protecovasaurus – a non-dinosaurian archosauriform Pamparaptor Protiguanodon – junior synonym of Psittacosaurus Panamericansaurus Protoavis – described as a bird, probably a chimera including theropod bones Pandoravenator Protoceratops Panguraptor Protognathosaurus - nomen dubium Panoplosaurus "Protognathus" – preoccupied name, now known as Protognathosaurus Panphagia Protohadros Pantydraco Protorosaurus – a non-dinosaurian reptile "Paraiguanodon" – nomen nudum; Bactrosaurus "Protorosaurus" – preoccupied name, now known as Chasmosaurus Paralititan "Protrachodon" – nomen nudum; Orthomerus Paranthodon "Proyandusaurus" – nomen nudum; Hexinlusaurus. Pararhabdodon Pseudolagosuchus – a non-dinosaurian dinosauromorph Parasaurolophus Psittacosaurus Pareiasaurus – a pareiasaur Pteropelyx - dubious hadrosauridae Parksosaurus Pterospondylus - dubious theropod Paronychodon - dubious troodontidae Puertasaurus Parrosaurus - now known as Hypsibema missouriensis Pukyongosaurus - nomen dubium Parvicursor Pulanesaura Patagonykus Pycnonemosaurus Patagosaurus Pyroraptor Patagotitan Pawpawsaurus .