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Re: Pachycephalosaur nasal airflow



The pdf is now free at the link:

http://onlinelibrary.wiley.com/doi/10.1002/ar.23046/abstract

On Tue, Oct 14, 2014 at 8:10 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
> A new paper:
>
> Jason M. Bourke, WM. Ruger Porter, Ryan C. Ridgely, Tyler R. Lyson,
> Emma R. Schachner, Phil R. Bell and Lawrence M. Witmer (2014)
> Breathing Life Into Dinosaurs: Tackling Challenges of Soft-Tissue
> Restoration and Nasal Airflow in Extinct Species.
> The Anatomical Record 297(11): 2148–2186
> Special Issue: Special Issue The Vertebrate Nose: Evolution,
> Structure, and Function
> DOI: 10.1002/ar.23046
> http://onlinelibrary.wiley.com/doi/10.1002/ar.23046/abstract
>
>
>
>
> The nasal region plays a key role in sensory, thermal, and respiratory
> physiology, but exploring its evolution is hampered by a lack of
> preservation of soft-tissue structures in extinct vertebrates. As a
> test case, we investigated members of the “bony-headed” ornithischian
> dinosaur clade Pachycephalosauridae (particularly Stegoceras validum)
> because of their small body size (which mitigated allometric concerns)
> and their tendency to preserve nasal soft tissues within their
> hypermineralized skulls. Hypermineralization directly preserved
> portions of the olfactory turbinates along with an internal nasal
> ridge that we regard as potentially an osteological correlate for
> respiratory conchae. Fossil specimens were CT-scanned, and nasal
> cavities were segmented and restored. Soft-tissue reconstruction of
> the nasal capsule was functionally tested in a virtual environment
> using computational fluid dynamics by running air through multiple
> models differing in nasal soft-tissue conformation: a bony-bounded
> model (i.e., skull without soft tissue) and then models with soft
> tissues added, such as a paranasal septum, a scrolled concha, a
> branched concha, and a model combining the paranasal septum with a
> concha. Deviations in fluid flow in comparison to a phylogenetically
> constrained sample of extant diapsids were used as indicators of
> missing soft tissue. Models that restored aspects of airflow found in
> extant diapsids, such as appreciable airflow in the olfactory chamber,
> were judged as more likely. The model with a branched concha produced
> airflow patterns closest to those of extant diapsids. These results
> from both paleontological observation and airflow modeling indicate
> that S. validum and other pachycephalosaurids could have had both
> olfactory and respiratory conchae. Although respiratory conchae have
> been linked to endothermy, such conclusions require caution in that
> our re-evaluation of the reptilian nasal apparatus indicates that
> respiratory conchae may be more widespread than originally thought,
> and other functions, such as selective brain temperature regulation,
> could be important.