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.

This work was supported by the Chancellerie des Universités de Paris, the Jurassic Foundation, the C.N.R.S., the European Community (TMR programme), the Fondation des Treilles, the Collège de France, and the Committee on Research of the University of California, Berkeley. F. Knoll is supported by a ‘Ramón y Cajal’ research contract from the Ministerio de Ciencia e Innovación (Madrid). This is UCMP Publication No. 1992.

Article in press.

Peer reviewed