Neornithischia

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Neornithischians
Temporal range: Early JurassicLate Cretaceous, 199.6–66 Ma
HypsilophodonBrussels.jpg
Hypsilophodon skeletal mount at the Brussels Science Institute
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Clade: Genasauria
Clade: Neornithischia
Cooper, 1985
Subgroups

Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. It is the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs. Neornithischians include a variety of basal forms historically known as "hypsilophodonts", including the Parksosauridae; in addition, there are derived forms classified in the groups Marginocephalia and Ornithopoda. The former includes clades Pachycephalosauria and Ceratopsia, while the latter typically includes Hypsilophodon and the more derived Iguanodontia.

Classification[edit]

Neornithischia was first named by Cooper in 1985 and defined as "all genasaurians more closely related to Parasaurolophus walkeri Parks, 1922, than to Ankylosaurus magniventris Brown, 1908 or Stegosaurus stenops Marsh, 1877a".[1]

A 2017 study by Matthew G. Baron, David B. Norman, and Paul M. Barrett recovered the Early Jurassic taxon Lesothosaurus diagnosticus from Southern Africa as the most basal known member of Neornithischia – a position previously held by Stormbergia dangershoeki (a taxon considered by the authors to be an adult form of Lesothosaurus and therefore a junior subjective synonym). However, Baron et al. go on to state that this result is only poorly supported and that future studies will be needed in order to better resolve the base of the ornithischian tree.[2]

The below cladogram follows an analysis by Clint A. Boyd published in 2015 on the relationships of neornithischians:[3]

Ornithischia

Pisanosaurus mertii

Heterodontosauridae

Genasauria

Thyreophora

Neornithischia

Stormbergia dangershoeki

Agilisaurus louderbacki

Hexinlusaurus multidens

Yandusaurus hongheensis

Leaellynasaura amicagraphica

Jeholosauridae

Yueosaurus tiantaiensis

Jeholosaurus shangyuanensis

Othnielosaurus consors

Cerapoda

Marginocephalia

Ornithopoda

Parksosauridae
Orodrominae

Oryctodromeus cubicularis

Koreanosaurus boseongensis

Zephyrosaurus schaffi

Kaiparowits ornithopod

Orodromeus makelai

Thescelosaurinae

Changchunsaurus parvus

Haya griva

Parksosaurus warreni

Thescelosaurus neglectus

Thescelosaurus assiniboiensis

Thescelosaurus garbanii

Elasmaria

Macrogryphosaurus gondwanicus

Notohypsilophodon comodorensis

Talenkauen santacrucensis

The cladogram below results from analysis by Herne et al., 2019.[4] Parksosaurus and Elasmaria were recovered within Ornithopoda, among other revised relationships.

Ornithischia

Heterodontosauridae

Eocursor

Thyreophora

Neornithischia

Lesothosaurus

Agilisaurus

Hexinlusaurus

Yandusaurus

Nanosaurus

Jeholosauridae

Haya

Jeholosaurus

Changchunsaurus

Thescelosauridae

Orodromeus

Koreanosaurus

Zephyrosaurus

Yueosaurus

Thescelosaurus

Cerapoda

Marginocephalia

Ornithopoda

Parksosaurus

Elasmaria

Talenkauen

Macrogryphosaurus

Gasparinisaura

Galleonosaurus

Leaellynasaura

Anabisetia

Diluvicursor

Clypeodonta

Hypsilophodon

Iguanodontia

Rhabdodontidae

Muttaburrasaurus

Tenontosaurus

Dryomorpha

References[edit]

  1. ^ Richard J. Butler; Paul Upchurch; David B. Norman (2008). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology. 6 (1): 1–40. doi:10.1017/S1477201907002271.
  2. ^ Matthew G. Baron; David B. Norman; Paul M. Barrett (2016). "Postcranial anatomy of Lesothosaurus diagnosticus (Dinosauria: Ornithischia) from the Lower Jurassic of southern Africa: implications for basal ornithischian taxonomy and systematics". Zoological Journal of the Linnean Society. doi:10.1111/zoj.12434.
  3. ^ Clint. A Boy (2015). "The systematic relationships and biogeographic history of ornithischian dinosaurs". PeerJ. 3 (e1523). doi:10.7717/peerj.1523. PMC 4690359. PMID 26713260.
  4. ^ Herne, Matthew C.; Nair, Jay P.; Evans, Alistair R.; Tait, Alan 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 and Vickers-Rich, 1999". Journal of Paleontology. doi:10.1017/jpa.2018.95.

External links[edit]