page_title: Ankylopollexia
section_title: Classification
hierarchical_section_title: Ankylopollexia / Classification
caption_attribution_description: Hand of Iguanodon shown in the Natural History Museum.
context_page_description: 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.
  The name stems from the Greek word, “ankylos”, mistakenly taken to mean stiff, fused, and the Latin word, “pollex”, meaning thumb. Originally described in 1986 by Sereno, this most likely synapomorphic feature of a conical thumb spine defines the clade.
  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. Even though they grew to be quite large, comparable to some carnivorous dinosaurs, they were universally herbivorous.
context_section_description: About 157 million years ago, Ankylopollexia and Dryosauridae are believed to have split into separate evolutionary branches. Originally named and described in 1986 by Paul Sereno, Ankylopollexia would receive a more formal definition in a later paper by Sereno in 2005. In the 1986 paper, the groups Camptosauridae and Styracosterna were used to define the clade, but in the 2005 paper, a phylogenetic definition was given: the last common ancestor of the species Camptosaurus dispar and Parasaurolophus walkeri and all its descendants.
  The cladogram below follows the phylogenetic analysis of Bertozzo et al. (2017).
caption: Hand of Iguanodon, showing the distinctive thumb of the group
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