Ankylopollexia

Ankylopollexia Temporal range: Late Jurassic–Late Cretaceous, 156–66 Ma PreЄ Є O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Ornithischia
Suborder:	†Ornithopoda
Clade:	†Dryomorpha
Clade:	†Ankylopollexia Sereno, 1986
Subgroups
Camptosauroidea Styracosterna Barilium Cedrorestes Cumnoria Dakotadon Darwinsaurus Draconyx Hippodraco Huxleysaurus Hypselospinus Iguanacolossus Kukufeldia Lanzhousaurus Mantellodon Morelladon Osmakasaurus Owenodon Planicoxa Proplanicoxa Sellacoxa Theiophytalia Uteodon Hadrosauriformes Delapparentia Iguanodon Lurdusaurus Ouranosaurus Proa Hadrosauroidea

Ankylopollexia is a clade of herbivorous iguanodontian dinosaurs that lived from the Late Jurassic to Late Cretaceous in all continents. Some members include Camptosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". The Ankylopollexia was named by Paul Sereno in 1986 to denote the group within the Iguanodontia that includes the Camptosauridae and the Styracosterna. The name means "stiff thumbs", referring to a possible synapomorphy, possessing a conical thumb spine.^[1] 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.

Phylogeny

The first definition of Ankylopollexia was given by Sereno in 1998. It was defined as the node-based taxon consisting of the last common ancestor of Camptosaurus, Parasaurolophus and all his descendants. Sereno (2005) improved this definition, using the type species, Camptosaurus dispar (Marsh 1879) and Parasaurolophus walkeri (Parks 1922), instead of the genera. Many ankylopollexians have not yet been included in a large phylogenetic analyses, or are too fragmentary to place confidently. These include Bihariosaurus (a nomen nudum), Delapparentia, Draconyx, Hypselospinus, Lurdusaurus, Osmakasaurus, Owenodon, Planicoxa, Proplanicoxa^[2] and Sellacoxa.^[2]

The cladogram below follows an analysis by Andrew McDonald, 2012.^[3]

Iguanodontia	Rhabdodontidae Tenontosaurus Dryomorpha Dryosauridae Ankylopollexia Camptosaurus Styracosterna Uteodon Hippodraco Theiophytalia Iguanacolossus Lanzhousaurus Kukufeldia Barilium Hadrosauriformes Iguanodon Hadrosauroidea (including Mantellisaurus, and Xuwulong)

References

1. Sereno, P.C. (1986). "Phylogeny of the bird-hipped dinosaurs (order Ornithischia)". National Geographic Research 2 (2): 234–56.
2. Carpenter, K. and Ishida, Y. (2010). "Early and "Middle" Cretaceous Iguanodonts in Time and Space" (PDF). Journal of Iberian Geology 36 (2): 145–164. doi:10.5209/rev_JIGE.2010.v36.n2.3.
3. McDonald, A. T. (2012). Farke, Andrew A, ed. "Phylogeny of Basal Iguanodonts (Dinosauria: Ornithischia): An Update". PLoS ONE 7 (5): e36745. doi:10.1371/journal.pone.0036745. PMC 3358318. PMID 22629328.