Introduction

Abstract

The Ornithopoda, one of five suborders within the Ornithischia, was originally proposed by Marsh in 1881 to include those bipedal dinosaurs possessing a predentary bone fitted over the rostral end of the mandibles. Ornithopods as recognized today can be further characterized by moderately long facial skeletons equipped with well-developed, often toothless premaxillae and moderate to large external nares. Maxillary and dentary dentitions vary but usually consist of at least one replacement series beneath the functional set; some have many rows of successional teeth. Tooth morphology suggests ornithopods were successful herbivores but, as will be discussed, the precise way(s) in which ornithopods chewed their food, hence lending important information about their trophic position, has not been settled. Postcranially, ornithopods show specialization for bipedality in hindlimb construction and lack well-developed protective structures on their flanks, back, and tail.