The taxonomy and phylogeny of basal iguanodonts (Dinosauria: Ornithischia)

Basal iguanodonts are one of the most abundant, diverse, and widespread types of dinosaur and also among the longest studied. Despite their copious fossil record, the phylogenetic relationships of many basal iguanodonts have not been quantitatively tested. Furthermore, it is perhaps a consequence of their long-studied status that numerous tangles have arisen in the taxonomy of basal iguanodonts, with many species assigned and reassigned to different genera without the aid of rigorous phylogenetic analysis. Finally, as with many dinosaurian groups, the fossil record of basal iguanodonts has expanded dramatically in recent years, especially by discovery of new species in the western United States and China. In an effort to address these lingering issues in basal iguanodont taxonomy and phylogeny, I set out to assemble the first comprehensive phylogenetic analysis of basal iguanodonts, to examine fossils of many species firsthand, and to fully describe the anatomy of several new or cursorily described taxa. The results are four papers on new basal iguanodont taxa from Utah and England and revision of some existing taxa, two papers fully describing the anatomy of Eolambia from Utah and Equijubus from China, and a paper on the phylogeny of basal iguanodonts. Although the relationships of some basal iguanodonts remain ambiguous, the taxonomic framework and phylogenetic data matrix developed in this dissertation will serve as the basis for future macroevolutionary studies of basal iguanodonts