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Prosaurolophus cranial anatomy

From: Ben Creisler

A new paper:

Christopher T. McGarrity, Nicolas E. Campione & David C. Evans (2013)
Cranial anatomy and variation in Prosaurolophus maximus (Dinosauria:
Zoological Journal of the Linnean Society 167(4): 531–568
DOI: 10.1111/zoj.12009

Prosaurolophus maximus Brown is a saurolophine hadrosaurid known from
numerous complete, articulated skulls from the Dinosaur Park Formation
(Campanian, Alberta, Canada) that range in size by approximately half
a metre in total skull length. Therefore, it is an important taxon for
understanding patterns of growth and variation in saurolophines. This
study describes the cranial anatomy of P. maximus from the type
locality of Dinosaur Provincial Park (Dinosaur Park Formation:
Campanian) on the basis of ten articulated skulls, quantitatively
examines its range of osteological variation, and provides the first
hypothesized ontogenetic series for this taxon. A second species,
Prosaurolophus blackfeetensis Horner, was named on the basis of
geologically younger material from Montana (Two Medicine Formation:
Campanian) that is diagnosed by putative morphological differences in
the nasal crest. However, considerable nasal crest variation in the
sample from the Dinosaur Park Formation does not permit quantitative
differentiation of P. blackfeetensis from P. maximus. Furthermore, a
species-level phylogenetic analysis of saurolophines that includes
both P. maximus and P. blackfeetensis as originally defined recovers
them as sister taxa that do not differ morphologically in the
character matrix. Based on both the morphometric and phylogenetic
data, this study supports the hypothesis that P. blackfeetensis is a
junior synonym of P. maximus, thereby substantially increasing its
temporal range to 1.6 million years, and a concomitant period of
morphological stasis in this taxon.