Neuroanatomy of the Upper Cretaceous turtle Chedighaii hutchisoni Gaffney, Tong & Meylan, 2006 (Pleurodira, Bothremydidae)
- Published
- Accepted
- Subject Areas
- Neuroscience, Paleontology, Zoology, Radiology and Medical Imaging
- Keywords
- Neuroanatomy, Paleoneurology, Bothremydidae, 3D reconstruction, CT scan
- Copyright
- © 2015 Deantoni
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. Neuroanatomy of the Upper Cretaceous turtle Chedighaii hutchisoni Gaffney, Tong & Meylan, 2006 (Pleurodira, Bothremydidae) PeerJ PrePrints 3:e1008v1 https://doi.org/10.7287/peerj.preprints.1008v1
Abstract
Background. While Computed Tomography scanning is a powerful non-invasive tool for the study of paleoneurology, the neuroanatomy of turtles remains unexplored in comparison to other higher taxa. I herein present data on the morphology of intracranial structures of Chedighaii hutchisoni based on CT scan generated endocasts. Methods. The CT scan of C. hutchisoni (KUVP 14765, holotype) was virtually manipulated using software Mimics (Materialise) v.10.01, with manual correction and preparation of internal structures in coronal view. Results. The endocast presents poorly demarcated flexures and cartilaginous rider, and cerebral hemisphere region larger than medulla. The abducens nerve (CNVI) canal is slightly curved and thinner than the internal carotid canal (cci). The semicircular canals are approximately the same caliber as the cci. The anterior (csa) and posterior (csp) semicircular canals form an angle of 80° and are equally elevated. The facial nerve (CNVII) canal is short and extends posterolaterally into the prootic; the junction with the cci happens at mid-length of the CNVII canal. One ramus of the statoacustic nerve (CNVIII) is visible. In the ophistotic there is one paired foramina for the glossopharyngeal nerve (CNIX). Discussion. The endocast of C. hutchisoni is in many aspects similar to the other bothremydids Galianemys whitei and G. emringeri, with some particularities. The canal of CNVI shows an intermediate condition between G. whitei (shorter, thinner than cci and rounded, handle-shaped) and G. emringeri (longer, thicker than cci and almost rectilinear). The semicircular canals are slightly thicker than in other studied pelomedusoids and chelids (e.g. Chelus fimbriatus and Elseya dentata), and the bony labyrinth is similar to that of G. emringeri, although in both Galianemys species the csa is more elevated than the csp in the common crus. The angle between csa and csp is also similar to G. emringeri and other pelomedusoids such as Podocnemis unifilis, P. expansa, Caninemys tridentata and Peltocephalus dumerillianus. C. hutchisoni presents one paired foramina for CNIX, not visible in both Galianemys species. Compared to an endocast of C. barberi (originally misidentified as Bothremys sp.), C. hutchisoni presents greater cerebrum/medulla width proportion, the cci of C. barberi is thicker and enters the sella turcica in a acuter angle, and CNVI is visible in ventral view in C. barberi, whereas in C. hutchisoni it hides beneath the cci. Further studies will help elucidate the variation of intracranial structures in Bothremydidade and in the remaining pleurodires families.
Author Comment
This is an abstract which has been accepted for the 5th Turtle Evolution Symposium.