Iguanodontidae

Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia. The clade is formally defined in the PhyloCode by Daniel Madzia and colleagues in 2021 as "the largest clade containing Iguanodon bernissartensis, but not Hadrosaurus foulkii".

Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynamism; there exists evidence for both bipedalism and quadrupedalism within iguanodontid species, supporting the idea that individual organisms were capable of both locomoting exclusively with their hind limbs and locomoting quadrupedally. Iguanodontids possess hoof-like second, third, and fourth digits, and in some cases, a specialized thumb spike and an opposable fifth digit. Their skull construction allows for a strong chewing mechanism called a transverse power stroke. This, paired with their bilateral dental occlusion, made them extremely effective as herbivores. Members of Iguanodontidae are thought to have had a diet that consisted of both gymnosperms and angiosperms, the latter of which co-evolved with the iguanodontids in the Cretaceous period.