Hypsilophodonts were small ornithopod dinosaurs. The group traditionally has included almost all ornithopods other than iguanodonts, but recent phylogenetic analyses have found that the group is mostly paraphyletic and the taxa within usually represent a stepwise arrangement leading up to Iguanodontia (Weishampel et al., 2003; Norman et al, 2004). Thus, the only certain member at this time is Hypsilophodon.