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Re: Ankylosaur hyobranchial apparatus resembled that of birds (free pdf)



The pdf is now free:

http://onlinelibrary.wiley.com/doi/10.1111/zoj.12293/pdf

On Tue, Jul 14, 2015 at 8:43 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
>
> A new online paper:
>
>
> Robert V. Hill, Michael D. D'Emic, G. S. Bever and Mark A. Norell (2015)
> A complex hyobranchial apparatus in a Cretaceous dinosaur and the
> antiquity of avian paraglossalia.
> Zoological Journal of the Linnean Society (advance online publication)
> DOI: 10.1111/zoj.12293
> http://onlinelibrary.wiley.com/doi/10.1111/zoj.12293/abstract
>
>
>
> The highly specialized feeding apparatus of modern birds is
> characterized in part by paraglossalia, triangular bones or cartilages
> in the tongue that constitute part of the rarely fossilized
> hyobranchial apparatus. Here, we report on a new, juvenile specimen of
> the ankylosaurid dinosaur Pinacosaurus grangeri Gilmore, 1933 that
> provides the first evidence of paraglossalia outside of crown group
> Aves. The specimen is remarkable in preserving a well-ossified
> hyobranchial apparatus, including paired paraglossalia, first and
> second ceratobranchials, epibranchials, and evidence of a median
> cartilaginous basihyal. Reassessment of Edmontonia, another
> ankylosaur, also reveals evidence of bony paraglossalia. Ankylosaur
> paraglossalia closely resemble those of birds, but are relatively
> larger and bear prominent muscle scars, supporting the hypothesis that
> ankylosaurs had fleshy, muscular tongues. The other hyobranchial
> elements, surprisingly, resemble those of terrestrially feeding
> salamanders. Ankylosaurs had reduced, slowly replacing teeth, as
> evidenced from dental histology, suggesting that they relied greatly
> on their tongues and hyobranchia for feeding. Some curved, rod-like
> elements of other dinosaur hyobranchia are reinterpreted as second
> ceratobranchials, rather than first ceratobranchials as commonly
> construed. Ankylosaurs provide rare fossil evidence of deep homology
> in vertebrate branchial arches and expose severe biases against the
> preservation and collection of the hyobranchial apparatus. In light of
> these biases, we hypothesize that paraglossalia were present in the
> common ancestor of Dinosauria, indicating that some structures of the
> highly derived avian feeding apparatus were in place by the Triassic
> Period.