Dinosaur classification began in 1842 when Sir Richard Owen placed ''

Iguanodon ''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to Early Cretaceous, Taxonomy (bi ...

'', ''

Megalosaurus ''Megalosaurus'' (meaning "great lizard", from Ancient Greek, Greek , ', meaning 'big', 'tall' or 'great' and , ', meaning 'lizard') is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch (Bathonian stage, 166 ...

'', and '' Hylaeosaurus'' in "a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

ia." 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 image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

of dinosaurs. The largest change was prompted by entomologist Willi Hennig's work in the 1950s, which evolved into modern

cladistics Cladistics ( ; from Ancient Greek 'branch') is an approach to Taxonomy (biology), biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesiz ...

. For specimens known only from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s, the rigorous analysis of characters to determine evolutionary relationships between different groups of animals (''clades'') proved incredibly useful. As computer-based cladistics matured in the 1990s, paleontologists were among the first zoologists to broadly 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

As most dinosaur paleontologists have advocated a shift away from traditional, ranked

Linnaean taxonomy Linnaean taxonomy can mean either of two related concepts: # The particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his ''Systema Naturae'' (1735) and subsequent works. In the taxonomy of Linnaeus th ...

in favor of rankless

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

systems, few ranked taxonomies of dinosaurs have been published since the 1980s. The following schema is among the most recent, 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 A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

), 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. Michael Benton classifies all dinosaurs within the Series Amniota, Class

Sauropsida Sauropsida (Greek language, Greek for "lizard faces") is a clade of amniotes, broadly equivalent to the Class (biology), class Reptile, Reptilia, though typically used in a broader sense to also include extinct stem-group relatives of modern repti ...

, Subclass Diapsida, Infraclass Archosauromorpha, Division

Archosaur Archosauria () or archosaurs () is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only extant taxon, extant representatives. Although broadly classified as reptiles, which traditionally exclude birds, the cladistics ...

ia, Subdivision

Avemetatarsalia Avemetatarsalia (meaning "bird metatarsals") is a clade of diapsid Reptile, reptiles containing all archosaurs more closely related to birds than to crocodilians. The two most successful groups of avemetatarsalians were the dinosaurs and pterosau ...

, 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 Theropoda (; from ancient Greek iktionary:θηρίον, , (''therion'') "wild beast"; wiktionary:πούς, , wiktionary:ποδός, (''pous, podos'') "foot" is one of the three major groups (Clade, clades) of Dinosaur, dinosaurs, alon ...

** †Infraorder Herrerasauria ** †Infraorder Coelophysoidea ** †Infraorder Ceratosauria+ *** †Parvorder Neoceratosauria+ **** †Superfamily Abelisauroidea ***** †Family Abelisauridae ***** †Family Noasauridae **** †Family Ceratosauridae ** Infraorder Tetanurae *** †Superfamily Megalosauroidea **** †Family Megalosauridae **** †Family Spinosauridae *** †Parvorder Carnosauria **** †Superfamily Allosauroidea ***** †Family Allosauridae ***** †Family Carcharodontosauridae ***** †Family Neovenatoridae ***** †Family Metriacanthosauridae *** Parvorder Coelurosauria **** †Family Coeluridae **** Division Maniraptoriformes ***** †Family Tyrannosauridae ***** †Family Ornithomimidae ***** Subdivision Maniraptora ****** †Family Alvarezsauridae ****** †Family Therizinosauridae ****** †Infradivision Deinonychosauria ******* †Family Troodontidae ******* †Family

Dromaeosauridae Dromaeosauridae () is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from ...

****** Class Aves * †Suborder Sauropodomorpha ** †Genus '' Thecodontosaurus'' ** †Family Plateosauridae ** †Genus '' Riojasaurus'' ** †Family

Massospondylidae Massospondylidae is a family (biology), family of early massopod dinosaurs that existed in Asia, Africa, North America, South America and AntarcticaHellert, Spencer M. "A New Basal Sauropodomorph from The Early Jurassic Hanson Formation of Antarc ...

** †Infraorder

Sauropoda Sauropoda (), whose members are known as sauropods (; from ''wikt:sauro-, sauro-'' + ''wikt:-pod, -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative t ...

*** †Family Vulcanodontidae *** †Family Omeisauridae *** †Parvorder Neosauropoda **** †Family Cetiosauridae **** †Family Diplodocidae **** †Division

Macronaria Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

***** †Family Camarasauridae ***** †Subdivision Titanosauriformes ****** †Family Brachiosauridae ****** †Infradivision Somphospondyli ******* †Family Euhelopodidae ******* †Family Titanosauridae

†Order Ornithischia

* †Family Pisanosauridae * †Family Fabrosauridae * †Suborder Thyreophora ** †Family Scelidosauridae ** †Infraorder

Stegosauria Stegosauria is a group of Herbivore, herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous Period (geology), periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere (North America, Europe a ...

*** †Family Huayangosauridae *** †Family Stegosauridae ** †Infraorder

Ankylosauria Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs ...

*** †Family Nodosauridae *** †Family Ankylosauridae * †Suborder Cerapoda ** †Infraorder Pachycephalosauria ** †Infraorder

Ceratopsia Ceratopsia or Ceratopia ( or ; Ancient Greek, Greek: "horned faces") is a group of herbivore, herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period (geology), Period, although ance ...

*** †Family Psittacosauridae *** †Family

Protoceratopsidae Protoceratopsidae is a family of basal (primitive) ceratopsians from the Late Cretaceous period. Although ceratopsians have been found all over the world, protoceratopsids are only definitively known from Cretaceous strata in Asia, with most spec ...

*** †Family

Ceratopsidae Ceratopsidae (sometimes spelled Ceratopidae) is a family of ceratopsian dinosaurs including ''Triceratops'', ''Centrosaurus'', and ''Styracosaurus''. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are k ...

** †Infraorder Ornithopoda *** †Family Heterodontosauridae *** †Family Hypsilophodontidae *** †Family Iguanodontidae * *** †Family

Hadrosauridae Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fam ...

Weishampel / Dodson / Osmólska classification

The following is based on the second edition of ''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

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

(''

Triceratops ''Triceratops'' ( ; ) is a genus of Chasmosaurinae, chasmosaurine Ceratopsia, ceratopsian dinosaur that lived during the late Maastrichtian age of the Late Cretaceous Period (geology), period, about 68 to 66 million years ago on the island ...

''/'' Stegosaurus'') * Herrerasauria ('' Herrerasaurus'' > ''Liliensternus'', '' Plateosaurus'') ** Herrerasauridae (''Herrerasaurus'' + '' Staurikosaurus'') * ? '' Eoraptor lunensis'' * Sauropodomorpha ('' Saltasaurus'' >

) ** ? ''

Saturnalia Saturnalia is an Roman festivals, ancient Roman festival and holiday in honour of the List of Roman deities, god Saturn (mythology), Saturn, held on 17 December in the Julian calendar and later expanded with festivities until 19 December. By t ...

tupiniquim'' ** ? Thecodontosauridae ** Prosauropoda ('' Plateosaurus'' >

) *** ? Thecodontosauridae *** ? Anchisauria ('' Anchisaurus'' + '' Melanorosaurus'') **** ? Anchisauridae (''Anchisaurus'' > ''Melanorosaurus'') **** ? Melanorosauridae (''Melanorosaurus'' > ''Anchisaurus'') *** Plateosauria ('' Jingshanosaurus'' + ''Plateosaurus'') ****

**** Yunnanosauridae **** Plateosauridae (''Plateosaurus'' > ''Yunnanosaurus'', '' Massospondylus'') **

(''Saltasaurus'' > ''Plateosaurus'') *** ? Anchisauridae *** ? Melanorosauridae *** Blikanasauridae *** Vulcanodontidae ***

Eusauropoda Eusauropoda (meaning "True Lizard Foot") is a derived clade of sauropod dinosaurs. Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of '' Shunosaurus'', and possibly '' Barapas ...

('' Shunosaurus'' + ''Saltasaurus'') **** ? Euhelopodidae **** Mamenchisauridae **** Cetiosauridae ('' Cetiosaurus'' > ''Saltasaurus'') **** Neosauropoda ('' Diplodocus'' + ''Saltasaurus'') ***** Diplodocoidea (''Diplodocus'' > ''Saltasaurus'') ****** Rebbachisauridae ('' Rebbachisaurus'' > ''Diplodocus'') ****** Flagellicaudata ******* Dicraeosauridae ('' Dicraeosaurus'' > ''Diplodocus'') ******* Diplodocidae (''Diplodocus'' > ''Dicraeosaurus'', '' Apatosaurus'') *****

(''Saltasaurus'' > ''Diplodocus'') ****** ? '' Jobaria tiguidensis'' ****** Camarasauromorpha ('' Camarasaurus'' + ''Saltasaurus'') ******* Camarasauridae ******* Titanosauriformes (''

Brachiosaurus ''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about . It was first Species description, described by American paleontologist Elmer S. Riggs in 1903 in paleontology, 1903 from fossi ...

'' + ''Saltasaurus'') ******** Brachiosauridae (''Brachiosaurus'' > ''Saltasaurus'') ********

Titanosauria Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of Sauropoda, sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with tax ...

(''Saltasaurus'' > ''Brachiosaurus'') ********* Andesauridae ********* Lithostrotia ('' Malawisaurus'' + ''Saltasaurus'') ********** '' Isisaurus colberti'' ********** '' Paralititan stromeri'' ********** Nemegtosauridae ********** Saltasauridae ('' Opisthocoelicaudia'' + ''Saltasaurus'') *

('' Passer domesticus'' > ''Cetiosaurus oxoniensis'') ** ? '' Eoraptor lunensis'' ** ? Herrerasauridae ** Ceratosauria ('' Ceratosaurus nasicornis'' > Aves) *** ? Coelophysoidea (''

Coelophysis ''Coelophysis'' ( Traditional English pronunciation of Latin, traditionally; or , as heard more commonly in recent decades) is a genus of coelophysid Theropoda, theropod dinosaur that lived Approximation, approximately 215 to 201.4 million y ...

'' > ''Ceratosaurus'') **** ? '' Dilophosaurus wetherilli'' **** Coelophysidae (''

'' + ''

Megapnosaurus ''Megapnosaurus'' (meaning "big dead lizard", from Greek μέγα = "big", ἄπνοος = "not breathing", "dead", σαῦρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago du ...

'') *** ? 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 ''Spinosaurus'' (; ) is a genus of large spinosaurid theropod dinosaurs that lived in what now is North Africa during the Cenomanian faunal stage, stage of the Late Cretaceous Period (geology), period, about 100 to 94 annum, million year ...

aegyptiacus'' > ''P. domesticus'') **** Megalosauridae (''

bucklandii'' > ''P. domesticus'', ''S. aegyptiacus'', ''Allosaurus fragilis'') ***** Megalosaurinae (''M. bucklandii'' > '' Eustreptospondylus oxoniensis'') ***** Eustreptospondylinae (''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 ''Compsognathus'' (; Ancient Greek, Greek ''kompsos''/κομψός; "elegant", "refined" or "dainty", and ''gnathos''/γνάθος; "jaw") is a genus of small, bipedalism, bipedal, carnivore, carnivorous theropoda, theropod dinosaur. Members o ...

longipes'' > ''P. domesticus'') ***** '' Proceratosaurus bradleyi'' ***** '' Ornitholestes hermanni'' ***** Tyrannoraptora (''

Tyrannosaurus ''Tyrannosaurus'' () is a genus of large theropod dinosaur. The type species ''Tyrannosaurus rex'' ( meaning 'king' in Latin), often shortened to ''T. rex'' or colloquially t-rex, is one of the best represented theropods. It lived througho ...

rex'' + ''P. domesticus'') ****** '' Coelurus fragilis'' ****** Tyrannosauroidea (''T. rex'' > '' Ornithomimus velox'', ''

Deinonychus ''Deinonychus'' ( ; ) is a genus of Dromaeosauridae, dromaeosaurid Theropoda, theropod dinosaur with one described species, ''Deinonychus antirrhopus''. This species, which could grow up to long, lived during the early Cretaceous Period (ge ...

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 ('' Gallimimus'' bullatus + '' 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 ''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in th ...

mongoliensis'') ***********

(''

Microraptor ''Microraptor'' (Greek language, Greek, μικρός, ''mīkros'': "small"; Latin language, Latin, ''raptor'': "one who seizes") is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovere ...

zhaoianus'' + '' Sinornithosaurus millenii'' + ''V. mongoliensis'') **********

Avialae Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds, and their closest relatives. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to Deinonychosauria, deinonychosaurs, though ...

('' Archaeopteryx'' + Neornithes)

Ornithischia

(''

''/''Triceratops'' > ''Cetiosaurus''/''Tyrannosaurus'') * ? ''

Lesothosaurus ''Lesothosaurus'' is a Monotypic taxon, monospecific genus of ornithischian dinosaur that lived during the Early Jurassic in what is now South Africa and Lesotho. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from L ...

diagnosticus'' * ? Heterodontosauridae * Genasauria ('' Ankylosaurus'' + ''Triceratops'') ** Thyreophora (''Ankylosaurus'' > ''Triceratops'') *** Scelidosauridae *** Eurypoda (''Ankylosaurus'' + ''Stegosaurus'') ****

(''Stegosaurus'' > ''Ankylosaurus'') ***** Huayangosauridae (''Huayangosaurus'' > ''Stegosaurus'') ***** Stegosauridae (''Stegosaurus'' > ''Huayangosaurus'') ****** '' Dacentrurus armatus'' ****** Stegosaurinae (''Stegosaurus'' > ''Dacentrurus'') ****

(''Ankylosaurus'' > ''Stegosaurus'') ***** Ankylosauridae (''Ankylosaurus'' > ''Panoplosaurus'') ****** '' Gastonia burgei'' ****** '' Shamosaurus scutatus'' ****** Ankylosaurinae (''Ankylosaurus'' > ''Shamosaurus'') ***** Nodosauridae (''Panoplosaurus'' > ''Ankylosaurus'') ** Cerapoda (''Triceratops'' > ''Ankylosaurus'') *** Ornithopoda ('' Edmontosaurus'' > ''Triceratops'') **** ? ''

diagnosticus'' **** ? Heterodontosauridae **** Euornithopoda ***** '' Hypsilophodon foxii'' ***** '' Thescelosaurus neglectus'' ***** Iguanodontia (''Edmontosaurus'' > ''Thescelosaurus'') ****** '' Tenontosaurus tilletti'' ****** Rhabdodontidae ****** Dryomorpha ******* Dryosauridae ******* Ankylopollexia ******** Camptosauridae ******** Styracosterna ********* '' Lurdusaurus arenatus'' ********* Iguanodontoidea (= Hadrosauriformes) ********** Iguanodontidae **********

(''Telmatosaurus'' + '' Parasaurolophus'' + ''

Corythosaurus ''Corythosaurus'' (; ) is a genus of hadrosaurid "duck-billed" dinosaur from the Late Cretaceous Period (geology), period, about 77–75.7 million years ago, in what is now Laramidia, western North America. Its name is derived from the Anci ...

'') *********** '' Telmatosaurus transsylvanicus'' *********** Euhadrosauria ************ Lambeosaurinae ************ Saurolophinae (= Hadrosaurinae) *** Marginocephalia **** Pachycephalosauria ('' Pachycephalosaurus wyomingensis'' > ''Triceratops horridus'') ***** Goyocephala (''Goyocephale'' + ''Pachycephalosaurus'') ****** Homalocephaloidea ('' Homalocephale'' + ''Pachycephalosaurus'') ******* Homalocephalidae ******* Pachycephalosauridae ****

(''Triceratops'' > ''Pachycephalosaurus'') ***** Psittacosauridae *****

Neoceratopsia Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period, although ancestral forms lived earlier, in the Late Ju ...

****** Coronosauria *******

******* Bagaceratopidae ******* Ceratopsoidea ********

Leptoceratopsidae Leptoceratopsidae is an extinct family (biology), family of neoceratopsian dinosaurs from Asia, North America and possibly Europe. Leptoceratopsids resembled, and were closely related to, other neoceratopsians, such as the family (biology), famil ...

******** Ceratopsomorpha *********

(''

'' + '' Styracosaurus'') ********** Centrosaurinae ********** Chasmosaurinae sigmalphasaurinae

Baron / Norman / Barrett classification

In 2017 Matthew G. Baron and his colleagues published a new analysis proposing to put Theropoda (except Herrerasauridae) and Ornithischia within a group called Ornithoscelida (a name originally coined by Thomas Henry Huxley in 1870), redefining Saurischia to cover Sauropodomorpha and Herrerasauridae. Amongst other things this would require hypercarnivory to have evolved independently for Theropoda and Herrerasauridae. This scheme is currently debated among palaeontologists, with recent studies finding little difference between the traditional and newly proposed models. *Dinosauria ** Ornithoscelida *** Ornithischia ***

** Saurischia *** Sauropodomorpha *** Herrerasauridae

Cau 2018

In his paper about the stepwise evolution of the avian bauplan, Cau (2018) found in the parsimony analysis a polytomy between herrerasaur-grade taxa, Sauropodomorpha and the controversial Ornithoscelida. The Bayesian analysis, however, found weak support for the sister grouping of Dinosauria and Herrerasauria, but strong support for the dichotomy between Sauropodomorpha and Ornithoscelida, as shown below:

Footnotes

References

* * * . * {{cite book , last = Weishampel , first = David B. , editor=Dodson, Peter , editor2=Osmólska, Halszka , title = The Dinosauria, Second Edition. , publisher = University of California Press. , year=2004 , url =https://archive.org/details/dinosauriandedit00weis , url-access = limited , isbn = 0-520-24209-2 , page
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pp * Systems of animal taxonomy