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A single most parsimonious tree recovered showing the phylogenetic position of Yinlong downsi and the interrelationships of the Cerapoda. The proposed tree plotted against geological time indicates the timing of the major cranial changes among the Ceratopsia. The Marginocephalia node is supported by 22 synapomorphies and the Heterodontosauriformes by nine synapomorphies (see electronic supplementary material).
