[N] 2007 Crest ontogeny in the genus Parasaurolophus
Evans, D.C., Reisz, R.R., and Dupuis, K. 2007. A juvenile Parasaurolophus (Ornithischia: Hadrosauridae) braincase from Dinosaur Provincial Park, Alberta, with comments on crest ontogeny in the genus. Journal of Vertebrate Paleontology 27(3):642-650.
Abstract: An incomplete braincase of a juvenile lambeosaurine hadrosaurid (Dinosauria: Ornithischia) is recognized as the second and smallest cranial specimen of Parasaurolophus from the Belly River Group (Campanian), Alberta, Canada. This specimen provides the first information on the ontogeny of the skull roof and autapomorphic tubular crest in this widely recognized yet poorly known taxon.
In addition to the distinctive morphology of the cranial crest, Parasaurolophus is characterized by a suite of skull roof characters associated with crest development that manifest at small size, including verticalization of the nasal frontal joint at the base of the crest. Although the crest is not preserved in the specimen described here, the distinctively thickened and steeply angled frontal platform indicates that the crest and facial profile were significantly different from the equivalent juvenile stages of corythosaurin lambeosaurines (Corythosaurus, Hypacrosaurus, Lambeosaurus), which resemble one another closely. Parasaurolophus therefore appears to deviate from the well-known corythosaurin mode of cranial crest growth early in ontogenetic development.