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Re: Skull ornamentation in juvenile Pachycephalosaurus fossils from Upper Cretaceous Hell Creek Formation



Sorry. Same fix to this ref to prevent the url rewrite and redirect:

Mark B. Goodwin & David C. Evans (2016)
The early expression of squamosal horns and parietal ornamentation
confirmed by new end-stage juvenile Pachycephalosaurus fossils from
the Upper Cretaceous Hell Creek Formation, Montana.
Journal of Vertebrate Paleontology (advance online publication)
DOI: 10.1080/02724634.2016.1078343
http: // www.tandfonline.com/doi/full/10.1080/02724634.2016.1078343

On Sat, Feb 6, 2016 at 10:27 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
>
> A new paper:
>
>
> Mark B. Goodwin & David C. Evans (2016)
> The early expression of squamosal horns and parietal ornamentation
> confirmed by new end-stage juvenile Pachycephalosaurus fossils from
> the Upper Cretaceous Hell Creek Formation, Montana.
> Journal of Vertebrate Paleontology (advance online publication)
> DOI: 10.1080/02724634.2016.1078343
> https://urldefense.proofpoint.com/v2/url?u=http-3A__&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=nA9RsiTGGbkmKz3MgOz4zb3aTfEXNvTjwal-fmC3xhQ&s=m7KNFKuqoulZyFw_kfHXgWHQMo9SOe-4mcEOtnfta04&e=
>   www.tandfonline.com/doi/full/10.1080/02724634.2016.1078343
>
> New end-stage juvenile specimens of Pachycephalosaurus from the Upper
> Cretaceous Hell Creek Formation, Montana, confirm the earliest
> expression of squamosal nodes, parietal ornamentation, and jugal
> morphology in the smallest and presumably youngest individuals yet
> known. High-resolution computed tomography of the slightly thickened,
> undomed parietal reveals a dense cortex, a highly cancellous interior
> of irregularly shaped erosion cavities, and bony trabeculae indicative
> of primary, fast growing bone. The parietal, with its highly
> ornamented septum morphology and patent sutures, is nearly identical
> to the holotype of ‘Dracorex hogwartsia,’ and combined with these new
> internal histological details, supports the alternative interpretation
> that ‘D. hogwartsia’ is a juvenile Pachycephalosaurus wyomingensis.
> The squamosal nodes grow into an array of horns and secondary nodes
> exemplified by the pachycephalosaurin ‘Stygimoloch spinifer’
> considered in this study to be a subadult P. wyomingensis. Unlike the
> squamosal ornamentation, the hypertrophied midline row of parietal
> nodes is transient as the frontoparietal dome expands later in
> ontogeny. We propose the term ‘ontogimorph’ as a substitute for
> ‘semaphoront’ to describe these taxon-specific morphological variants
> that grow allometrically and express extreme cranial morphology along
> a postnatal growth continuum ontogenetically. These juvenile-,
> sub-adult-, and adult-specific features in the skull of
> Pachycephalosaurus may have allowed the visual identification of
> ontogimorphs and signal their changing sociobiological status.