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The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction.
J Anat. 2011 Dec; 219(6):661-75.JA

Abstract

Internal cranial anatomy is a challenging area to study in fossilized skulls because of small sample sizes and varied post-mortem preservational alterations. This difficulty has led to the lack of correspondence between results obtained from direct osteological observation and from more indirect reconstruction methods. This paper presents corroborating evidence from direct osteological observation and from reconstruction based on computed X-ray tomography (CT) on the internal cranial anatomy of the ankylosaurid dinosaur Euoplocephalus tutus. A remarkable specimen of Euoplocephalus preserves rarely observed internal cranial structures such as vascular impressions in the nasal cavity, olfactory turbinates and possible impressions of conchae. Comparison with fossils and CT models of other taxa and other Euoplocephalus specimens adds osteological evidence for the previously reconstructed nasal cavity in this dinosaur and revises the previously described braincase morphology. A new interpretation of the ethmoidal homology identifies a mesethmoid, sphenethmoid and ectethmoid. These ethmoidal ossifications are continuous with the mineralized walls of the nasal cavity. The location of the olfactory fenestra provides further evidence that the olfactory regions of the nasal cavity are pushed to the sides of the main airway. This implies that the function of the vascular impressions in the nasal cavity and the looping of the cavity are not related to olfaction. A byproduct of the elongate, looping airway is a dramatic increase in surface area of the nasal respiratory mucosa, which in extant species has been linked to heat and water balance. A role in vocalization as a resonating chamber is another possible function of the looping and elongation of the nasal cavity. Olfaction remains as a possible function for the enlarged olfactory region, suggesting that multiple functions account for different parts of the ankylosaurid nasal cavity that underwent substantial modification. Cranial endocasts show negligible variation within Euoplocephalus, which lends some confidence to interspecific comparisons of endocranial morphology.

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Authors+Show Affiliations

Miyashita T
Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada. tetsuto@ualberta.ca
Arbour VM
No affiliation info available
Witmer LM
No affiliation info available
Currie PJ
No affiliation info available

MeSH

AnimalsDinosaursFossilsImage Processing, Computer-AssistedNasal CavitySkullTomography, X-Ray Computed

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

21954840

Citation

Miyashita, Tetsuto, et al. "The Internal Cranial Morphology of an Armoured Dinosaur Euoplocephalus Corroborated By X-ray Computed Tomographic Reconstruction." Journal of Anatomy, vol. 219, no. 6, 2011, pp. 661-75.
Miyashita T, Arbour VM, Witmer LM, et al. The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction. J Anat. 2011;219(6):661-75.
Miyashita, T., Arbour, V. M., Witmer, L. M., & Currie, P. J. (2011). The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction. Journal of Anatomy, 219(6), 661-75. https://doi.org/10.1111/j.1469-7580.2011.01427.x
Miyashita T, et al. The Internal Cranial Morphology of an Armoured Dinosaur Euoplocephalus Corroborated By X-ray Computed Tomographic Reconstruction. J Anat. 2011;219(6):661-75. PubMed PMID: 21954840.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction. AU - Miyashita,Tetsuto, AU - Arbour,Victoria M, AU - Witmer,Lawrence M, AU - Currie,Philip J, Y1 - 2011/09/29/ PY - 2011/9/30/entrez PY - 2011/10/1/pubmed PY - 2012/1/6/medline SP - 661 EP - 75 JF - Journal of anatomy JO - J Anat VL - 219 IS - 6 N2 - Internal cranial anatomy is a challenging area to study in fossilized skulls because of small sample sizes and varied post-mortem preservational alterations. This difficulty has led to the lack of correspondence between results obtained from direct osteological observation and from more indirect reconstruction methods. This paper presents corroborating evidence from direct osteological observation and from reconstruction based on computed X-ray tomography (CT) on the internal cranial anatomy of the ankylosaurid dinosaur Euoplocephalus tutus. A remarkable specimen of Euoplocephalus preserves rarely observed internal cranial structures such as vascular impressions in the nasal cavity, olfactory turbinates and possible impressions of conchae. Comparison with fossils and CT models of other taxa and other Euoplocephalus specimens adds osteological evidence for the previously reconstructed nasal cavity in this dinosaur and revises the previously described braincase morphology. A new interpretation of the ethmoidal homology identifies a mesethmoid, sphenethmoid and ectethmoid. These ethmoidal ossifications are continuous with the mineralized walls of the nasal cavity. The location of the olfactory fenestra provides further evidence that the olfactory regions of the nasal cavity are pushed to the sides of the main airway. This implies that the function of the vascular impressions in the nasal cavity and the looping of the cavity are not related to olfaction. A byproduct of the elongate, looping airway is a dramatic increase in surface area of the nasal respiratory mucosa, which in extant species has been linked to heat and water balance. A role in vocalization as a resonating chamber is another possible function of the looping and elongation of the nasal cavity. Olfaction remains as a possible function for the enlarged olfactory region, suggesting that multiple functions account for different parts of the ankylosaurid nasal cavity that underwent substantial modification. Cranial endocasts show negligible variation within Euoplocephalus, which lends some confidence to interspecific comparisons of endocranial morphology. SN - 1469-7580 UR - https://www.unboundmedicine.com/medline/citation/21954840/The_internal_cranial_morphology_of_an_armoured_dinosaur_Euoplocephalus_corroborated_by_X_ray_computed_tomographic_reconstruction_ L2 - https://doi.org/10.1111/j.1469-7580.2011.01427.x DB - PRIME DP - Unbound Medicine ER -