What is "ankylopollexia"

Ankylopollexia is an extinct clade of dinosaurs within the order Ornithischia that lived from the Late Jurassic to the Late Cretaceous. It is considered a more derived clade of iguanodontians and contains the subgroup Styracosterna and Hadrosauriformes. The name stems from the Greek word, “ankylos”, meaning 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. Many ankylopollexians have not yet been placed in the phylogeny because of the lack of data on the specimens or simply just not analyzed yet. One of the most famous and most derived members of the Ankylopollexia clade is the Iguanodon.

First appearing around 156 million years ago, Ankylopollexia died out as a clade around 65.5 million years ago. Mostly found in China, Eastern and Western Europe, and the Western United States, ankyllopolexians not have been found in Africa or South America. Even though they grew to be quite large, comparable to some carnivorous dinosaurs, they were herbivorous iguanodontians. Most ankylopollexians were bipedal. However, most, also when grazing or moving slowly, would stand on all fours because of their shorter forelimbs.