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Re: Juvenile chasmosaurine from Dinosaur Park Formation, Alberta, Canada (free pdf)



Note that the pdf is now free:


http://www.tandfonline.com/doi/pdf/10.1080/02724634.2015.1048348

On Mon, Jan 11, 2016 at 1:05 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
> A new paper:
>
> Philip J. Currie, Robert B. Holmes, Michael J. Ryan & Clive Coy (2016)
> A juvenile chasmosaurine ceratopsid (Dinosauria, Ornithischia) from
> the Dinosaur Park Formation, Alberta, Canada.
> Journal of Vertebrate Paleontology (advance online publication)
> DOI:10.1080/02724634.2015.1048348
> http://www.tandfonline.com/doi/full/10.1080/02724634.2015.1048348
>
>
> An articulated, 1.5 m long skeleton of a juvenile Chasmosaurus,
> lacking only the front limbs, pectoral girdles, and terminal caudal
> vertebrae, was collected from the Dinosaur Park Formation in Dinosaur
> Provincial Park, Alberta. The short, tall skull has a narrow frill
> that lacks a posterior embayment. Many of the cranial bones are
> co-ossified in spite of the small size of the specimen. The nasals
> form an incipient horncore, and the short, knob-like postorbital
> horncore lacks sinuses. The palpebral is not fused to the rest of the
> skull. The frontal fontanelle is keyhole-shaped. The triangular
> squamosal extends to the back of the parietals. Epiossifications are
> lacking, although the squamosal margin is thick and scalloped. The
> parietal has a pronounced midline sagittal crest. Parietal fenestrae,
> if present, would have been narrow and elongate. There are only 18
> maxillary tooth positions. The syncervical comprises three
> co-ossified, but distinct vertebrae. Anterior caudal vertebrae support
> unfused caudal ribs. Ossified tendons in the neck, trunk, and sacrum
> do not extend into the tail. Hind limb proportions are comparable to
> those of adult ceratopsids. The pedal unguals are distally acute. Skin
> impressions are similar to those of mature chasmosaurines.
> Phylogenetic analysis, if all characters are coded as they are seen,
> suggests that the specimen is a basal chasmosaurine. When size or age
> dependent characters are recoded as ‘?,’ the specimen groups with
> other Chasmosaurus. These characters should only be used in
> phylogenetic analyses when all specimens are mature.