Iguanodontia

Iguanodontia Temporal range: Middle Jurassic–Late Cretaceous, 163–66 Ma PreЄ Є O S D C P T J K Pg N
Heads of different iguanodontians
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Ornithischia
Clade:	†Cerapoda
Suborder:	†Ornithopoda
Clade:	†Iguanodontia Dollo, 1888
Subgroups[1]
†Tenontosaurus †Rhabdodontidae †Elasmaria[2] †Anabisetia †Gasparinisaura †Macrogryphosaurus †Morrosaurus †Notohypsilophodon †Talenkauen †Trinisaura †Dryomorpha †Dryosauroidea †Ankylopollexia

Iguanodontia is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Tenontosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodontians were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period.^[3] Derived iguanodontians (such as Muttaburrasaurus and many ankylopollexians) were generally large animals, and some (such as Shantungosaurus, which measured up to 50 ft (15 m) in length and weighed up to 8 tons) equaled the largest carnivorous dinosaurs in size.

Classification

Iguanodontia is often listed as an infraorder within a suborder Ornithopoda, though Benton (2004) lists Ornithopoda as an infraorder and does not rank Iguanodontia. Traditionally, iguanodontians were grouped into the superfamily Iguanodontoidea and family Iguanodontidae. However, phylogenetic studies show that the traditional "iguanodontids" are a paraphyletic grade leading up to the hadrosaurs (duck-billed dinosaurs). Groups like Iguanodontoidea are sometimes still used as unranked clades in the scientific literature, though many traditional "iguanodontids" are now included in the more inclusive group Hadrosauroidea. Iguanodontia is usually defined as the most inclusive group containing Parasaurolophus walkeri but not Hypsilophodon foxii or Thescelosaurus neglectus, or other combinations of species that would ultimately result in the same group in most modern analyses. The group was first defined as a clade in 2008 by Paul Sereno.^[4]

The cladogram below follows an analysis by Butler et al, 2011.^[1]

Ornithopoda	Orodromeus Hypsilophodon Zephyrosaurus Yandusaurus Changchunsaurus Jeholosaurus Gasparinisaura Parksosaurus Bugenasaura Thescelosaurus Iguanodontia Talenkauen Anabisetia Rhabdodontidae Tenontosaurus T. tilletti T. dossi Dryomorpha Dryosauridae Ankylopollexia (including Iguanodon, hadrosaurids, and others)

References

1. Richard J. Butler, Jin Liyong, Chen Jun, Pascal Godefroit (2011). "The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China". Palaeontology 54 (3): 667–683. doi:10.1111/j.1475-4983.2011.01046.x.
2. 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.
3. McDonald, A.T.; Kirkland, J.I.; DeBlieux, D.D.; Madsen, S.K.; Cavin, J.; Milner, A.R.C.; Panzarin, L. (2010). Farke, Andrew Allen, ed. "New Basal Iguanodontians from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs". PLoS ONE 5 (11): e14075. doi:10.1371/journal.pone.0014075. PMC 2989904. PMID 21124919.
4. Sereno, P.C. (2005). "Stem Archosauria Version 1.0." TaxonSearch. Available: http://www.taxonsearch.org/Archive/stem-archosauria-1.0.php via the Internet. Accessed 24 November 2010.