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Nov 22, 2022 · As in other turtles, the optic nerve (CN II) is the thickest among the cranial nerves in T. scripta (Fig. 4.4). It emerges from the optic stalk of the anteroventral brain surface dorsal to the infundibulum, takes a sharp lateral turn through the optic foramen, which is encased in chondrocranial cartilage, and then continues forward to the eyeball.
- Introduction
- Materials and Methods
- Results
- Discussion
- Author Contributions
- Funding
- Conflict of Interest Statement
- Acknowledgments
- Supplementary Material
Turtles (Testudinata sensu Joyce et al., 2004) are a diverse group of reptiles with an unusual “bauplan” fundamentally different from that of other amniotes. Unique morphological characters, including the anapsid cranial configuration, which lacks temporal fenestrations, and the presence of a bony shell formed by a dorsal carapace and a ventral pla...
For digital reconstruction of endocranial anatomy (brain, inner ear, neurovascular structures, nasal cavity) two specimens of Proganochelys quenstedti from the Late Triassic of Germany were studied: MB 1910.45.2 (Museum für Naturkunde Berlin) from the Baerecke and Limpricht Quarry, Halberstadt (Jaekel, 1918), and SMNS 16980 (Staatliches Museum für ...
Endocranial Anatomy
The reconstruction of MB 1910.45.2 (Figures 1A–D) provided most details of the endocranial anatomy, but exhibited some moderate medio-lateral deformation. In comparison, the reconstruction of SMNS 16980 (Figures 1E–H) showed no obvious artifacts, but the poor grayscale contrast permitted only a few structures (i.e., brain, pituitary fossa and some cranial nerves) to be visualized. In combination, both specimens allowed for a detailed reconstruction of most endocranial components. The brain en...
Endocast Outline Analysis
The morphology of the endocast of Proganochelys quenstedti was compared to different turtles and other amniote taxa using shape analysis. The PCA results show that the first three PCs account for 71.7% (Table 2) of the brain endocast outline shape variation (Figures 5, 6). In no PC plot, there is a clear separation between either the phylogenetic or the ecological groups considered. However, the PERMANOVA tests support that Lepidosauromorpha differs significantly from Archosauromorpha (p = 0....
Ancestral Condition for Testudinata
Even though more taxa have been assigned to the turtle stem-lineage recently (Li et al., 2008; Lyson et al., 2010; Schoch and Sues, 2015), Proganochelys quenstedti remains one of the most important stem-turtles, given its phylogenetic position as the earliest shelled turtle with a completely preserved skull (Parsons, 1959, 1970; Halpern, 1992; Joyce et al., 2016). Its endocast is a relatively simple structure when compared to that of crown-turtles (Carabajal et al., 2013; Mautner et al., 2017...
Sensory Capabilities of Proganochelys
The endosseous labyrinth of Proganochelys quenstedti is slightly distinct from that of crown-turtles in being more compact and robust, with short and thick semicircular canals and a low crus communis resulting in almost horizontally oriented canals (Figure 4). The anterior and posterior semicircular canals (ASC and PSC, respectively) are nearly at the same level as the lateral semicircular canal (LSC), whereas in other turtles the first two run dorsally in relation to the last (Carabajal et a...
Evolution of the Turtle Brain Endocast
In the shape analysis, Proganochelys quenstedti is not contained in the morphospace occupied by any of the considered phylogenetic groups (Figure 5). There is extensive overlap in the PCA plots, but, at the same time, the PERMANOVA test shows a separation between Lepidosauromorpha, Testudinata and Archosauromorpha (Table 3). These results suggest that all amniotes (excluding dinosaurs and mammals) share a similar plesiomorphic brain endocast morphology, but that those lineages evolved in diff...
SL and IW: conceived and designed the study; SL: performed the three-dimensional reconstruction; IW: provided digital datasets; SL, GF, and IW: collected, analyzed and interpreted the data; SL and GF: created figures and supplementary data; SL, GF, and IW: contributed equally to the discussion, preparation and writing of the paper.
This research was funded by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) grants 2016/03934-2 and 2014/2539-5 to GF and by SNF (Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung advanced postdoc mobility grant P300PA_164720 to IW.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We thank Daniela Schwarz for sharing the μCT-scan of the Berlin specimen, and Rainer Schoch for the permission to μCT the Stuttgart specimen of Proganochelys. We thank Walter G. Joyce, Bill Simpson and Virginie Volpato for access to the specimens and CT scan data of Naomichelys and Emys. Adrian Tröscher, Jan Prochel, Irina Ruf, and Kristin Mahlow a...
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fevo.2018.00007/full#supplementary-material
- Stephan Lautenschlager, Gabriel S. Ferreira, Gabriel S. Ferreira, Ingmar Werneburg, Ingmar Werneburg
- 2018
Sep 1, 2007 · They are innervated by short olfactory nerves that run into long olfactory tracts, which project caudally to olfactory bulbs. Animals with elongated snouts (eg, alligators, monitor lizards, aquatic turtles) have long olfactory tracts [1] leading from the olfactory bulbs to the cerebrum.
- Jeanette Wyneken
- 2007
Aug 17, 2022 · Therefore, turtles have been investigated to assess the molecular mechanisms of neuroprotective strategies used by them in anoxic conditions, such as maintaining low levels of glutamate, increasing adenosine and GABA, upregulating heat shock proteins, and downregulating K ATP channels.
- 10.3389/fnana.2022.937504
- 2022
- Front Neuroanat. 2022; 16: 937504.
Sep 19, 2019 · With a study of the network between nerve and muscle cells in turtles, researchers from the University of Copenhagen have gained new insight into the way in which movements are generated and...
Jun 1, 2019 · The present study revealed structural details of the nasal cavity and 3 independent sensory epithelia that project nerve bundles to the olfactory bulbs of juvenile green sea turtles. These findings provide a basic understanding of olfactory sensing in juveniles, and further studies will focus on adult sea turtles.
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Aug 21, 2019 · Chelonioid turtles are the only surviving group of reptiles that secondarily evolved marine lifestyles during the Mesozoic Early chelonioid evolution is documented by fossils of their stem group, such as protostegids, which yield insights into the evolution of marine adaptation.
