Processes on the premaxilla and prefrontals of Tsintaosaurus were missing or at least degraded in the fossilization process on the type specie cranium. The loss, absence, or degradation of these processes on the cranium of Tsintaosaurus led to the initial description of the hadrosaur as a uniquely ornamented ornithischian dinosaur. The absent portions of the crest left a surviving crest that was posteriorly angled in a way that made the unicorn-like horn extend dorsally superior to the midline of the cranium and directly above the orbits. The hypothesized full size crest arced rostrally before sweeping inferiorly to finish the articulation with the premaxilla and maxilla. The crest was not hypothesized to bulge rostrally but instead indented and arced inferio-posteriorly from the acme of the crest to the premaxilla. Sound production in the crest, as is often assumed in hadrosaurs (especially lambeosaurine hadrosaurs), is not documented or hypothesized at the current time that is any different from existing sound profiles. The unicorn horn was not considered to be relevant to vocalization as far as I have seen, but I have not read all of the literature as yet and this could therefore be a misrepresentation at the moment.