Ornithopoda

Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subsectio: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauria
Ordo: †Ornithischia
Cladus: †Genasauria
Cladus: †Neornithischia
Cladus: †Cerapoda
Cladus: †Ornithopoda
Cladus: †Euornithopoda
Genera incertae sedis: †Changchunsaurus – †Delapparentia – †Notohypsilophodon – †Siamodon – †Siluosaurus
secundum Herne et al., 2019

Cladus: †Ornithopoda
Cladi: †Elasmaria – †Iguanodontia
Genera incertae sedis: †Hypsilophodon – †Parksosaurus
Name

Ornithopoda Marsh, 1881: 423
References
Primary references

Marsh, O.C. 1881. Principal Characters of American Jurassic Dinosaurs. Part V. The American Journal of Science. Series 3 21(125): 417–423. BHL Reference page.

Additional references

Shibata, M. & Azuma, Y. 2015. New basal hadrosauroid (Dinosauria: Ornithopoda) from the Lower Cretaceous Kitadani Formation, Fukui, central Japan. Zootaxa 3914(4): 421–440. DOI: 10.11646/zootaxa.3914.4.3. Reference page.
Herne, M.C., Nair, J.P., Evans, A.R. & Tait, A.M. 2019. New small-bodied ornithopods (Dinosauria, Neornithischia) from the Early Cretaceous Wonthaggi Formation (Strzelecki Group) of the Australian-Antarctic rift system, with revision of Qantassaurus intrepidus Rich & Vickers-Rich, 1999. Journal of Paleontology 93(3): 543–584. DOI: 10.1017/jpa.2018.95 ResearchGate Reference page.

Vernacular names
polski: Ornitopody
українська: Ортіноподи

Ornithopoda (/ˌɔːrnəˈθɒpədə/)[2] is a clade of ornithischian dinosaurs, called ornithopods (/ˈɔːrnəθəˌpɒdz, ɔːrˈnɪθ-/),[3][4] that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, dominating the North American land. Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by a non-avian dinosaur, rivaling that of modern mammals such as the domestic cow. They reached their apex of diversity and ecological dominance in the hadrosaurids (colloquially known as 'duck-bills'), before they were wiped out by the Cretaceous–Paleogene extinction event along with all other non-avian dinosaurs. Members are known from all seven continents, though they are generally rare in the Southern Hemisphere.
History of research

In 1870, Thomas Henry Huxley listed Iguanodontidae (coined by Cope a year earlier[5]) as one of his three families of dinosaurs (alongside Megalosauridae and Scelidosauridae), including within it the genera Iguanodon, Hypsilophodon, and Hadrosaurus, in addition to Cetiosaurus and tentatively Stenopelix.[6] The term Ornithopoda was erected by Othniel Charles Marsh in 1881 as part of his then still ongoing investigation of the classification of Dinosauria. It was considered one of the four definite orders of dinosaurs, the others being Theropoda, Sauropoda, and Stegosauria (Hallopoda was considered a possible fifth). He subdivided the order into three families: Camptonotidae, Iguanodontidae, and Hadrosauridae; the former was a new name, whereas the latter two were carried over from the nomenclatures of Huxley and Edward Drinker Cope respectively. Within Camptonotidae he included the European Hypsilophodon and three American taxa he named himself, Camptonotus, Laosaurus, and Nanosaurus.[7] Camptonotus was in 1885 renamed to Camptosaurus, as the original name was pre-occupied by a cricket; the associated family followed suit, becoming Camptosauridae.[8] In Iguanodontidae, only found in Europe, he included Iguanodon and Vectisaurus. In Hadrosauridae, he included Hadrosaurus, Cionodon, and tentatively Agathaumas.[7]
Description
Three-toed feet of Iguanodon

Ornithopoda means "bird feet", from the Greek ornithos ("bird") and pous ("feet"); this is in reference to members’ characteristic three-toed feet, although many early forms retained four toes. They were also characterized as lacking in body armour, not developing a horny beak, having an elongated pubis (that eventually extended past the ilium), and having a missing hole in the lower jaw (a Mandibular fenestrae). A variety of ornithopods, and related cerapods, had thin cartilaginous plates along the outside of the ribs; in some cases, these plates mineralized and were fossilized. The function of these intercostal plates is unknown. They have been found with Hypsilophodon, Othnielosaurus, Parksosaurus, Talenkauen, Thescelosaurus,[9] and Macrogryphosaurus to date.[10]
Size of a variety of numerous ornithopods

The early ornithopods were only about 1 metre (3 feet) long, but probably very fast. They had a stiff tail, like the theropods, to help them balance as they ran on their hind legs. Later ornithopods became more adapted to grazing on all fours; their spines curved, and came to resemble the spines of modern ground-feeders, such as the bison. As they became more adapted to eating while bent over, they became facultative quadrupeds; still running on two legs, and comfortable reaching up into trees, but spending most of their time walking or grazing on all fours. The taxonomy of dinosaurs previously ascribed to the Hypsilophodontidae is problematic. The group previously consisted of all non-iguanodontian bipedal ornithischians, but a phylogenetic reappraisal has shown such species to be paraphyletic. As such, the hypsilophodont family is currently represented only by Hypsilophodon.[11]

Later ornithopods became larger, but never rivalled the incredible size of the long-necked, long-tailed sauropods that they partially supplanted. The very largest, such as Shantungosaurus, were as heavy as medium-sized sauropods (up to 23 metric tons/25 short tons), but never grew much beyond 15 metres (50 feet).
Classification
An artist's interpretation of Gideonmantellia, sometimes considered one of the most primitive ornithopods
Restoration of Muttaburrasaurus, an early iguanodont
Skeleton of Dysalotosaurus, a dryosaurid ornithopod from the Jurassic
Life restoration of Iguanacolossus, an early styracosternan
Reconstruction of Mantellisaurus, a primitive member of the Hadrosauriformes
Mounted skeleton of Edmontosaurus, a saurolophine hadrosaur, and one of the last ornithopods

Historically, most indeterminate ornithischian bipeds were lumped in as ornithopods. Most have since been reclassified.[citation needed]
Taxonomy

Ornithopoda is usually given the rank of Suborder, within the order Ornithischia. While ranked taxonomy has largely fallen out of favour among dinosaur paleontologists, some researchers have continued to employ such a classification, though sources have differed on what its rank should be. Benton (2004) placed it as an infraorder within the suborder Cerapoda (originally named as an unranked clade), while others, such as Ibiricu et al. 2010, have retained it at its traditional ranking of suborder.[12]
Phylogeny

In 2021, Ornithopoda was given a formal definition under the PhyloCode: "The largest clade containing Iguanodon bernissartensis but not Pachycephalosaurus wyomingensis and Triceratops horridus."[1] The cladogram below follows a 2017 analysis by Madzia et al.:[13]

Clypeodonta	Hypsilophodon Cerapoda Marginocephalia Ornithopoda Gideonmantellia Elasmaria Burianosaurus Iguanodontia Rhabdodontomorpha Muttaburrasaurus Rhabdodontidae Tenontosaurus Dryomorpha Dryosauridae Ankylopollexia Camptosaurus Styracosterna Iguanodon Hadrosauroidea

References

Madzia, D.; Arbour, V.M.; Boyd, C.A.; Farke, A.A.; Cruzado-Caballero, P.; Evans, D.C. (2021). "The phylogenetic nomenclature of ornithischian dinosaurs". PeerJ. 9: e12362. doi:10.7717/peerj.12362. PMC 8667728. PMID 34966571.
"Ornithopoda". Merriam-Webster Dictionary.
"ornithopod". Lexico UK English Dictionary. Oxford University Press. Archived from the original on December 13, 2021.
"ornithopod". Merriam-Webster Dictionary.
Cope, Edward D. (1969). "Synopsis of the extinct batrachia, reptilia and aves of North America". Transactions of the American Philosophical Society. 14 (1): 91. doi:10.5962/bhl.title.60499.
Wikisource reference Huxley, Thomas H. (1870). "On the Classification of the Dinosauria, with observations on the Dinosauria of the Trias". Quarterly Journal of the Geological Society of London. Vol. 26. pp. 32–51. doi:10.1144/gsl.jgs.1870.026.01-02.09 – via Wikisource.
Marsh, O. C. (1882). "Classification of the Dinosauria". American Journal of Science. 23 (133): 81–86. Bibcode:1882AmJS...23...81M. doi:10.2475/ajs.s3-23.133.81. S2CID 130836648.
Marsh, Othniel C. (1885). "Names of extinct reptiles" (PDF). American Journal of Science. 29: 169.
Butler, Richard J.; Galton, Peter M. (August 2008). "The 'dermal armour' of the ornithopod dinosaur Hypsilophodon from the Wealden (Early Cretaceous: Barremian) of the Isle of Wight: a reappraisal". Cretaceous Research. 29 (4): 636–642. doi:10.1016/j.cretres.2008.02.002.
Calvo, J. O.; Porfiri, J. D.; Novas, F. E. (2007). "Discovery of a new ornithopod dinosaur from the Portezuelo Formation (Upper Cretaceous), Neuquén, Patagonia, Argentina". Arquivos do Museu Nacional. 65 (4): 471–483.
Weishampel, D. B. & Heinrich, R. E. (1992). "Systematics of Hypsilophodontidae and basal Iguanodontia (Dinosauria: Ornithopoda)" (PDF). Historical Biology. 6 (3): 159–184. doi:10.1080/10292389209380426.
Ibiricu, Lucio M.; Martínez, Rubén D.; Lamanna, Matthew C.; Casal, Gabriel A.; Luna, Marcelo; Harris, Jerald D.; Lacovara, Kenneth J. (2010). "A Medium-Sized Ornithopod (Dinosauria: Ornithischia) from the Upper Cretaceous Bajo Barreal Formation of Lago Colhué Huapi, Southern Chubut Province, Argentina". Annals of Carnegie Museum. 79: 39–50. doi:10.2992/007.079.0103. S2CID 53407321.
Madzia, Daniel; Boyd, Clint A.; Mazuch, Martin (2017). "A basal ornithopod dinosaur from the Cenomanian of the Czech Republic". Journal of Systematic Palaeontology. 16 (11): 967–979. doi:10.1080/14772019.2017.1371258. S2CID 90008574.