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Description

Originally P. cyrtocristatus has been classified as a distinct species of Parasaurolophus, from the type P. walkeri due to the difference of the length and structure of the tubolar crest. Hopson has been the first to suggest that P. cyrtocristatus could have been the female form of another species of Parasaurolophus with longer crest (usually I synonymize P.tubicen with P.walkeri, but in the case P. cyrtocristatus is a female, the male would be more like P. tubicen than P. walkeri). As is demonstrated a high level of difference between the crests is present even in ontogenetically immature specimens and the same variability are found in other lambeosaurines too (both ontogenetical and sexual/inter-specific).
So, in your opinion, what are these? Two species of the same genus or two sexes of the same species? Is this sexual dimorphism or inter-specific dimorphism?

Description

Originally P. cyrtocristatus has been classified as a distinct species of Parasaurolophus, from the type P. walkeri due to the difference of the length and structure of the tubolar crest. Hopson has been the first to suggest that P. cyrtocristatus could have been the female form of another species of Parasaurolophus with longer crest (usually I synonymize P.tubicen with P.walkeri, but in the case P. cyrtocristatus is a female, the male would be more like P. tubicen than P. walkeri). As is demonstrated a high level of difference between the crests is present even in ontogenetically immature specimens and the same variability are found in other lambeosaurines too (both ontogenetical and sexual/inter-specific).
So, in your opinion, what are these? Two species of the same genus or two sexes of the same species? Is this sexual dimorphism or inter-specific dimorphism?