Ankylopollexia

Ankylopollexia is an extinct clade of dinosaurs within the Ornithischia. They lived from 156 to 66 million years ago. The name stems from the Greek word, “ankylos”, meaning stiff, fused, and the Latin word, “pollex”, meaning thumb. One of the most famous and most derived members of the Ankylopollexia clade is the Iguanodon. The Hadrosaurs are also in this group.

Ankylopollexia Temporal range: Late Jurassic–Late Cretaceous,
Mantellisaurus skeleton, Natural History Museum, London
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	Ornithischia
Clade:	Dryomorpha
Clade:	Ankylopollexia Sereno, 1986
Subgroups
†Camptosaurus †Cumnoria †Draconyx †Owenodon? †Uteodon †Styracosterna †Barilium †Bayannurosaurus †Cedrorestes †Dakotadon †Fukuisaurus †Hippodraco †Hypselospinus †Iguanacolossus †Lanzhousaurus †Lurdusaurus †Magnamanus †Osmakasaurus †Planicoxa †Proa †Theiophytalia †Hadrosauriformes †Bolong †Jinzhousaurus †Ouranosaurus †Morelladon †Iguanodontidae †Hadrosauroidea

Ankylopollexia Media

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  Size of three ankylopollexians (Edmontosaurus, Iguanodon, and Camptosaurus) compared to other ornithopods

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  Life restoration of Iguanacolossus

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  Hand of Iguanodon, showing the distinctive thumb of the group

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  A 1905 diagram showing the small size of an Edmontosaurus annectens brain (bottom; alongside that of Triceratops horridus, top) commented on in early sources

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  Endocast of an Amurosaurus brain in right lateral (A), dorsal (B), and ventral (C) views

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  Life restoration of Camptosaurus