Ankylopollexia

Ankylopollexia Temporal range: Late Jurassic–Late Cretaceous, 156.3–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Six ankylopollexian ornithopods (top left to bottom right): Shantungosaurus, Iguanodon, Tethyshadros, Uteodon, Olorotitan, Gongpoquansaurus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Neornithischia
Clade:	†Ornithopoda
Clade:	†Dryomorpha
Clade:	†Ankylopollexia Sereno, 1986
Subgroups
†Camptosaurus †Cumnoria †Draconyx †Oblitosaurus? †Owenodon? †Uteodon †Styracosterna †Batyrosaurus? †Bayannurosaurus †Burianosaurus? †Calvarius †Cedrorestes †Dakotadon †Fukuisaurus †Hippodraco †Iguanacolossus †Lanzhousaurus †Lurdusaurus †Magnamanus †Napaisaurus †Osmakasaurus †Planicoxa †Riabininohadros †Theiophytalia †Barilium †Hypselospinus †Proa †Hadrosauriformes †Bolong †Brighstoneus †Jinzhousaurus †Ouranosaurus †Morelladon †Iguanodontidae †Hadrosauroidea

Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna.^[1] The name stems from the Greek word, “ankylos”, mistakenly taken to mean stiff, fused (in fact the adjective means bent or curved; used of fingers, it can mean hooked), and the Latin word, “pollex”, meaning thumb. Originally described in 1986 by Sereno, a most likely synapomorphic feature of a conical thumb spine defines the clade.^[2]

First appearing around 156 million years ago, in the Jurassic, Ankylopollexia became an extremely successful and widespread clade during the Cretaceous, and were found around the world. The group died out at the end of the Maastrichtian.^[1] They grew to be quite large, comparable to some carnivorous dinosaurs and they were universally herbivorous.^[3]