Dinosaur classification



Dinosaur classification began in 1842 when Sir Richard Owen placed Iguanodon, Megalosaurus, and Hylaeosaurus in "a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria." In 1887 and 1888 Harry Seeley divided dinosaurs into the two orders Saurischia and Ornithischia, based on their hip structure. These divisions have proved remarkably enduring, even through several seismic changes in the taxonomy of dinosaurs.

The largest change was prompted by entomologist Willi Hennig's work in the 1950s, which evolved into modern cladistics. For specimens known only from fossils, the rigorous analysis of characters to determine evolutionary relationships between different groups of animals (clades) proved incredibly useful. When computer-based analysis using cladistics came into its own in the 1990s, paleontologists became among the first zoologists to almost wholeheartedly adopt the system. Progressive scrutiny and work upon dinosaurian interrelationships, with the aid of new discoveries that have shed light on previously uncertain relationships between taxa, have begun to yield a stabilizing classification since the mid-2000s. While cladistics is the predominant classificatory system among paleontology professionals, the Linnean system is still in use, especially in works intended for popular distribution.

Benton classification
The following schema is from the third edition of Vertebrate Palaeontology, a respected undergraduate textbook. While it is structured so as to reflect evolutionary relationships (similar to a cladogram), it also retains the traditional ranks used in Linnaean taxonomy. The classification has been updated from the second edition in 2000 to reflect new research, but remains fundamentally conservative.

Benton classifies all dinosaurs within the Series Amniota, Class Sauropsida, Subclass Diapsida, Infraclass Archosauromorpha, Division Archosauria, Subdivision Avemetatarsalia, Infradivision Ornithodira, and Superorder Dinosauria. Dinosauria is then divided into the two traditional orders, Saurischia and Ornithischia. The dagger (†) is used to indicate taxa with no living members.

Order Saurischia

 * Suborder Theropoda
 * †Infraorder Herrerasauria
 * †Infraorder Coelophysoidea
 * †Infraorder Ceratosauria
 * †Family Ceratosauridae
 * †Family Abelisauridae
 * Infraorder Tetanurae
 * †Division Carnosauria
 * †Sudivision Spinosauroidea
 * †Family Megalosauridae
 * †Family Spinosauridae
 * †Subdivision Allosauroidea
 * †Family Allosauridae
 * †Family Carcharodontosauridae
 * Division Coelurosauria
 * †Family Coeluridae
 * Subdivision Maniraptoriformes
 * †Family Tyrannosauridae
 * †Family Ornithomimidae
 * Infradivision Maniraptora
 * †Family Alvarezsauridae
 * †Family Therizinosauridae
 * †Cohort Deinonychosauria
 * †Family Troodontidae
 * †Family Dromaeosauridae
 * Avialae (birds)
 * †Suborder Sauropodomorpha
 * †Thecodontosaurus
 * †Family Plateosauridae
 * †Riojasaurus
 * †Family Massospondylidae
 * †Infraorder Sauropoda
 * †Family Vulcanodontidae
 * †Family Omeisauridae
 * †Division Neosauropoda
 * †Family Cetiosauridae
 * †Family Diplodocidae
 * †Subdivision Macronaria
 * †Family Camarasauridae
 * †Infradivision Titanosauriformes
 * †Family Brachiosauridae
 * †Cohort Somphospondyli
 * †Family Euhelopodidae
 * †Family Titanosauridae

†Order Ornithischia

 * †Family Pisanosauridae
 * †Family Fabrosauridae
 * †Suborder Thyreophora
 * †Family Scelidosauridae
 * †Infraorder Stegosauria
 * †Infraorder Ankylosauria
 * †Family Nodosauridae
 * †Family Ankylosauridae
 * †Suborder Cerapoda
 * †Infraorder Pachycephalosauria
 * †Infraorder Ceratopsia
 * †Family Psittacosauridae
 * †Family Protoceratopsidae
 * †Family Ceratopsidae
 * †Infraorder Ornithopoda
 * †Family Heterodontosauridae
 * †Family Hypsilophodontidae
 * †Family Iguanodontidae *
 * †Family Hadrosauridae

Weishampel/Dodson/Osmólska classification
The following is based on the second edition of the The Dinosauria, a compilation of articles by experts in the field that provided the most comprehensive coverage of Dinosauria available when it was first published in 1990. The second edition updates and revises that work.

The cladogram and phylogenetic definitions below reflect the current understanding of evolutionary relationships. The taxa and symbols in parentheses after a given taxa define these relationships. The plus symbol ("+") between taxa indicates the given taxa is a node-based clade, defined as comprising all descendants of the last common ancestor of the "added" taxa. The greater-than symbol (">") indicates the given taxon is a stem-based taxon, comprising all organisms sharing a common ancestor that is not also an ancestor of the "lesser" taxon.

Saurischia
(Tyrannosaurus/Allosaurus > Triceratops/Stegosaurus)
 * Herrerasauria (Herrerasaurus > Liliensternus, Plateosaurus)
 * Herrerasauridae (Herrerasaurus + Staurikosaurus)
 * ? Eoraptor lunensis
 * Sauropodomorpha (Saltasaurus > Theropoda)
 * ? Saturnalia tupiniquim
 * ? Thecodontosauridae
 * Prosauropoda (Plateosaurus > Sauropoda)
 * ? Thecodontosauridae
 * ? Anchisauria (Anchisaurus + Melanorosaurus)
 * ? Anchisauridae (Anchisaurus > Melanorosaurus'')
 * ? Melanorosauridae (Melanorosaurus > Anchisaurus)
 * Plateosauria (Jingshanosaurus + Plateosaurus)
 * Massospondylidae
 * Yunnanosauridae
 * Plateosauridae (Plateosaurus > Yunnanosaurus, Massospondylus)
 * Sauropoda (Saltasaurus > Plateosaurus)
 * ? Anchisauridae
 * ? Melanorosauridae
 * Blikanasauridae
 * Vulcanodontidae
 * Eusauropoda (Shunosaurus + Saltasaurus)
 * ? Euhelopodidae
 * Mamenchisauridae
 * Cetiosauridae (Cetiosaurus > Saltasaurus)
 * Neosauropoda (Diplodocus + Saltasaurus)
 * Diplodocoidea (Diplodocus > Saltasaurus)
 * Rebbachisauridae (Rebbachisaurus > Diplodocus)
 * Flagellicaudata
 * Dicraeosauridae (Dicraeosaurus > Diplodocus)
 * Diplodocidae (Diplodocus > Dicraeosaurus)
 * Macronaria (Saltasaurus > Diplodocus)
 * ? Jobaria tiguidensis
 * Camarasauromorpha (Camarasaurus + Saltasaurus)
 * Camarasauridae
 * Titanosauriformes (Brachiosaurus + Saltasaurus)
 * Brachiosauridae (Brachiosaurus > Saltasaurus)
 * Titanosauria (Saltasaurus > Brachiosaurus)
 * Andesauridae
 * Lithostrotia (Malawisaurus + Saltasaurus)
 * Isisaurus colberti
 * Paralititan stromeri
 * Nemegtosauridae
 * Saltasauridae (Opisthocoelicaudia + Saltasaurus)
 * Theropoda (Passer domesticus > Cetiosaurus oxoniensis)
 * ? Eoraptor lunensis
 * ? Herrerasauridae
 * Ceratosauria (Ceratosaurus nasicornis > Aves)
 * ? Coelophysoidea (Coelophysis > Ceratosaurus)
 * ? Dilophosaurus wetherilli
 * Coelophysidae (Coelophysis + Megapnosaurus)
 * ? Neoceratosauria (Ceratosaurus > Coelophysis)
 * Ceratosauridae
 * Abelisauroidea (Carnotaurus sastrei > C. nasicornis)
 * Abelisauria (Noasaurus + Carnotaurus)
 * Noasauridae
 * Abelisauridae (Abelisaurus comahuensis + C. sastrei)
 * Carnotaurinae (Carnotaurus > Abelisaurus)
 * Abelisaurinae (Abelisaurus > Carnotaurus)
 * Tetanurae (P. domesticus > C. nasicornis)
 * ? Spinosauroidea (Spinosaurus aegyptiacus > P. domesticus)
 * Megalosauridae (Megalosaurus bucklandii > P. domesticus, S. aegyptiacus, Allosaurus fragilis)
 * Megalosaurinae (M. bucklandii > Eustreptospondylus oxoniensis)
 * Eustreptospondlyinae (E. oxoniensis > M. bucklandii)
 * Spinosauridae (S. aegyptiacus > P. domesticus, M. bucklandii, A. fragilis)
 * Baryonychinae (Baryonyx walkeri > S. aegyptiacus)
 * Spinosaurinae (S. aegyptiacus > B. walkeri)
 * Avetheropoda (A. fragilis + P. domesticus)
 * Carnosauria (A. fragilis > Aves)
 * ? Spinosauroidea
 * Monolophosaurus jiangi
 * Allosauroidea (A. fragilis + Sinraptor dongi)
 * Allosauridae (A. fragilis > S. dongi, Carcharodontosaurus saharicus)
 * Sinraptoridae (S. dongi > A. fragilis, C. saharicus)
 * Carcharodontosauridae (C. saharicus > A. fragilis, S. dongi)
 * Coelurosauria (P. domesticus > A. fragilis)
 * Compsognathidae (Compsognathus longipes > P. domesticus)
 * Proceratosaurus bradleyi
 * Ornitholestes hermanni
 * Tyrannoraptora (Tyrannosaurus rex + P. domesticus)
 * Coelurus fragilis
 * Tyrannosauroidea (T. rex > Ornithomimus velox, Deinonychus antirrhopus, A. fragilis)
 * Dryptosauridae
 * Tyrannosauridae (T. rex + Tarbosaurus bataar + Daspletosaurus torosus + Albertosaurus sarcophagus + Gorgosaurus libratus)
 * Tyrannosaurinae (T. rex > A. sarcophagus)
 * Albertosaurinae (A. sarcophagus > T. rex)
 * Maniraptoriformes (O. velox + P. domesticus)
 * Ornithomimosauria (Ornithomimus edmontonicus + Pelecanimimus polyodon)
 * Harpymimidae
 * Garudimimidae
 * Ornithomimidae
 * Maniraptora (P. domesticus > O. velox)
 * Oviraptorosauria (Oviraptor philoceratops > P. domesticus)
 * Caenagnathoidea (O. philoceratops + Caenagnathus collinsi)
 * Caenagnathidae (C. collinsi > O. philoceratops)
 * Oviraptoridae (O. philoceratops > C. collinsi)
 * Oviraptorinae (O. philoceratops + Citipati osmolskae)
 * Therizinosauroidea (Therizinosaurus + Beipiaosaurus)
 * Alxasauridae
 * Therizinosauridae
 * Paraves (P. domesticus > O. philoceratops)
 * Eumaniraptora (P. domesticus + D. antirrhopus)
 * Deinonychosauria (D. antirrhopus > P. domesticus or Dromaeosaurus albertensis + Troodon formosus)
 * Troodontidae (T. formosus > Velociraptor mongoliensis)
 * Dromaeosauridae (Microraptor zhaoianus + Sinornithosaurus millenii + V. mongoliensis)
 * Avialae (Archaeopteryx + Neornithes)

Ornithischia
(Iguanodon/Triceratops > Cetiosaurus/Tyrannosaurus)
 * ? Lesothosaurus diagnosticus
 * ? Heterodontosauridae
 * Genasauria (Ankylosaurus + Triceratops)
 * Thyreophora (Ankylosaurus > Triceratops)
 * Scelidosauridae
 * Eurypoda (Ankylosaurus + Stegosaurus)
 * Stegosauria (Stegosaurus > Ankylosaurus)
 * Huayangosauridae (Huayangosaurus > Stegosaurus)
 * Stegosauridae (Stegosaurus > Huayangosaurus)
 * Dacentrurus armatus
 * Stegosaurinae (Stegosaurus > Dacentrurus)
 * Ankylosauria (Ankylosaurus > Stegosaurus)
 * Ankylosauridae (Ankylosaurus > Panoplosaurus)
 * Gastonia burgei
 * Shamosaurus scutatus
 * Ankylosaurinae (Ankylosaurus > Shamosaurus)
 * Nodosauridae (Panoplosaurus > Ankylosaurus)
 * Cerapoda (Triceratops > Ankylosaurus)
 * Ornithopoda (Edmontosaurus > Triceratops)
 * ? Lesothosaurus diagnosticus
 * ? Heterodontosauridae
 * Euornithopoda
 * Hypsilophodon foxii
 * Thescelosaurus neglectus
 * Iguanodontia (Edmontosaurus > Thescelosaurus)
 * Tenontosaurus tilletti
 * Rhabdodontidae
 * Dryomorpha
 * Dryosauridae
 * Ankylopollexia
 * Camptosauridae
 * Styracosterna
 * Lurdusaurus arenatus
 * Iguanodontoidea (=Hadrosauriformes)
 * Iguanodontidae
 * Hadrosauridae (Telmatosaurus + Parasaurolophus)
 * Telmatosaurus transsylvanicus
 * Euhadrosauria
 * Lambeosaurinae
 * Saurolophinae (=Hadrosaurinae)
 * Marginocephalia
 * Pachycephalosauria (Pachycephalosaurus wyomingensis > Triceratops horridus)
 * Goyocephala (Goyocephale + Pachycephalosaurus)
 * Homalocephaloidea (Homalocephale + Pachycephalosaurus'')
 * Homalocephalidae
 * Pachycephalosauridae
 * Ceratopsia (Triceratops > Pachycephalosaurus)
 * Psittacosauridae
 * Neoceratopsia
 * Coronosauria
 * Protoceratopsidae
 * Bagaceratopsidae
 * Ceratopsoidea
 * Leptoceratopsidae
 * Ceratopsomorpha
 * Ceratopsidae
 * Centrosaurinae
 * Chasmosaurinae