CRANIAL ANATOMY OF THE SMALL ORNITHISCHIAN DINOSAUR CHANGCHUNSAURUSPARVUS FROM THE QUANTOU FORMATION (CRETACEOUS: APTIAN-CENOMANIAN) OFJILIN PROVINCE, NORTHEASTERN CHINA

摘要

The Quantou Formation of Jilin Province, People's Republic of China, has recently yielded an important newfauna of 'middle' Cretaceous vertebrates. This fauna includes the small-bodied cerapodan ornithischian dinosaur Changchun-saurus parvus, represented by excellent cranial and postcranial material. When initially described, Changchunsaurus washypothesed to represent one of the most basal known ornithopods; however, similarities to ceratopsians were also noted,suggesting that Changchunsaurus may be crucial to elucidating the interrelationships of basal cerapodans, one of most prob-lematic areas of ornithischian phylogeny. Here we present a detailed description of the craniodental anatomy of Changchun-saurus, rediagnose the taxon based upon three autapomorphies, and provide comparisons to other basal cerapodans, as afoundation for future studies of basal cerapodan relationships. Changchunsaurus shows strong similarities to the ChineseEarly Cretaceous cerapodan Jeholosaurus, and it is likely that they are sister taxa.