Ontogenetic change and adult body size of the early ornithischian dinosaur Lesothosaurus diagnosticus: Implications for basal ornithischian taxonomy

Questions about the taxonomic status, diversity, and pace of evolution of basal ornithischian dinosaurs persist in part because some historically important taxa have been based on incomplete material of uncertain ontogenetic status. We examined the morphology of critical “fabrosaurid” specimens and analyzed the bone tissues of small and large individuals. We conclude that the case for the existence of a non-heterodontosaurid ornithischian distinct from Lesothosaurus diagnosticus in the upper Elliot Formation of southern Africa is not conclusive and we suggest that this species and Stormbergia dangershoeki may actually represent ontogenetic stages of one taxon that reached maturity in approximately four years.