Kingdom Animalia Class Reptilia Order †Ornithischia | Phylum Chordata Clade Dinosauria Clade †Genasauria | |
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Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs.
Classification
Neornithischia was first named by Cooper in 1985 and defined as "all genasaurians more closely related to Parasaurolophus walkeri Parks, 1922, than to Ankylosaurus magniventris Brown, 1908 or Stegosaurus stenops Marsh, 1877a". The cladogram below follows a 2011 analysis by paleontologists Richard J. Butler, Jin Liyong, Chen Jun and Pascal Godefroit.
A recent study by Matthew G. Baron, David B. Norman and Paul M. Barrett recovered the Early Jurassic taxon Lesothosaurus diagnosticus from Southern Africa as the most basal known member of Neornithischia – a position previously held by Stormbergia dangershoeki (a taxon considered by the authors to be an adult form of Lesothosaurus and therefore a junior subjective synonym). However, Baron et al. go on to state that this result is only poorly supported and that future studies will be needed in order to better resolve the base of the ornithischian tree. The cladogram below follows Baron et al. 2016.