Iguanodontid

Classification

In the past, Iguanodontidae became a waste-basket for any ornithopod that did not belong in either Hadrosauridae, or the now defunct Hypsilophodontidae. A number of studies suggest that Iguanodontidae as traditionally defined is paraphyletic with respect to Hadrosauridae. That is, iguanodontids represent successive steps in the acquisition of advanced hadrosaurian characteristics, and in this view cannot be defined as a single distinct clade. Nevertheless, some researchers have found support for a monophyletic Iguanodontidae consisting of a handful of genera. Some other studies, however, fail to recover the group. The left cladogram was recovered in a 2015 analysis that supports a monophyletic Iguanodontidae, whereas the right cladogram from 2012 study finds the group to be paraphyletic: