1
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Pochat‐Cottilloux Y, Rinder N, Perrichon G, Adrien J, Amiot R, Hua S, Martin JE. The neuroanatomy and pneumaticity of Hamadasuchus (Crocodylomorpha, Peirosauridae) from the Cretaceous of Morocco and its paleoecological significance for altirostral forms. J Anat 2023; 243:374-393. [PMID: 37309776 PMCID: PMC10439374 DOI: 10.1111/joa.13887] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 06/14/2023] Open
Abstract
We describe the endocranial structures of Hamadasuchus, a peirosaurid crocodylomorph from the late Albian-Cenomanian Kem Kem group of Morocco. The cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization, as well as the bones of the braincase of a new specimen, are reconstructed and compared with extant and fossil crocodylomorphs, which represent different lifestyles. Cranial bones of this specimen are identified as belonging to Hamadasuchus, with close affinities with Rukwasuchus yajabalijekundu, another peirosaurid from the 'middle' Cretaceous of Tanzania. The endocranial structures are comparable to those of R. yajabalijekundu but also to baurusuchids and sebecids (sebecosuchians). Paleobiological traits of Hamadasuchus, such as alert head posture, ecology, and behavior are explored for the first time, using quantitative metrics. The expanded but narrow semi-circular canals and enlarged pneumatization of the skull of Hamadasuchus are linked to a terrestrial lifestyle. Continuing work on the neuroanatomy of supposedly terrestrial crocodylomorphs needs to be broadened to other groups and will allow to characterize whether some internal structures are affected by the lifestyle of these organisms.
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Affiliation(s)
| | - Nicolas Rinder
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL‐TPEVilleurbanneFrance
| | | | - Jérôme Adrien
- Laboratoire MatériauxIngénierie et Science, Institut National des Sciences Appliquées de LyonVilleurbanneFrance
| | - Romain Amiot
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL‐TPEVilleurbanneFrance
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2
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Latimer AE, Sherratt E, Bonnet T, Scheyer TM. Semicircular canal shape diversity among modern lepidosaurs: life habit, size, allometry. BMC Ecol Evol 2023; 23:10. [PMID: 37046214 PMCID: PMC10091843 DOI: 10.1186/s12862-023-02113-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 04/03/2023] [Indexed: 04/14/2023] Open
Abstract
BACKGROUND The shape of the semicircular canals of the inner ear of living squamate reptiles has been used to infer phylogenetic relationships, body size, and life habits. Often these inferences are made without controlling for the effects of the other ones. Here we examine the semicircular canals of 94 species of extant limbed lepidosaurs using three-dimensional landmark-based geometric morphometrics, and analyze them in phylogenetic context to evaluate the relative contributions of life habit, size, and phylogeny on canal shape. RESULTS Life habit is not a strong predictor of semicircular canal shape across this broad sample. Instead, phylogeny plays a major role in predicting shape, with strong phylogenetic signal in shape as well as size. Allometry has a limited role in canal shape, but inner ear size and body mass are strongly correlated. CONCLUSIONS Our wide sampling across limbed squamates suggests that semicircular canal shape and size are predominantly a factor of phylogenetic relatedness. Given the small proportion of variance in semicircular canal shape explained by life habit, it is unlikely that unknown life habit could be deduced from semicircular canal shape alone. Overall, semicircular canal size is a good estimator of body length and even better for body mass in limbed squamates. Semiaquatic taxa tend to be larger and heavier than non-aquatic taxa, but once body size and phylogeny are accounted for, they are hard to distinguish from their non-aquatic relatives based on bony labyrinth shape and morphology.
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Affiliation(s)
- Ashley E Latimer
- Department of Palaeontology, University of Zurich, Karl Schmid-Strasse 4, 8006, Zurich, Switzerland
| | - Emma Sherratt
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Timothée Bonnet
- Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia
| | - Torsten M Scheyer
- Department of Palaeontology, University of Zurich, Karl Schmid-Strasse 4, 8006, Zurich, Switzerland.
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3
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Gaillard C, MacPhee RDE, Forasiepi AM. Seeing through the eyes of the sabertooth Thylacosmilus atrox (Metatheria, Sparassodonta). Commun Biol 2023; 6:257. [PMID: 36944801 PMCID: PMC10030895 DOI: 10.1038/s42003-023-04624-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/23/2023] [Indexed: 03/23/2023] Open
Abstract
The evolution of mammalian vision is difficult to study because the actual receptor organs-the eyes-are not preserved in the fossil record. Orbital orientation and size are the traditional proxies for inferring aspects of ocular function, such as stereoscopy. Adaptations for good stereopsis have evolved in living predaceous mammals, and it is reasonable to infer that fossil representatives would follow the same pattern. This applies to the sparassodonts, an extinct group of South American hypercarnivores related to marsupials, with one exception. In the sabertooth Thylacosmilus atrox, the bony orbits were notably divergent, like those of a cow or a horse, and thus radically differing from conditions in any other known mammalian predator. Orbital convergence alone, however, does not determine presence of stereopsis; frontation and verticality of the orbits also play a role. We show that the orbits of Thylacosmilus were frontated and verticalized in a way that favored some degree of stereopsis and compensated for limited convergence in orbital orientation. The forcing function behind these morphological tradeoffs was the extraordinary growth of its rootless canines, which affected skull shape in Thylacosmilus in numerous ways, including relative orbital displacement.
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Affiliation(s)
- Charlène Gaillard
- Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, CCT-CONICET Mendoza, Av. Ruiz Leal s/n, Parque General San Martín, CP5500, Mendoza, Argentina.
| | - Ross D E MacPhee
- Department of Mammalogy, American Museum of Natural History, 200 Central Park West, 10024-5102, New York, NY, USA
| | - Analía M Forasiepi
- Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, CCT-CONICET Mendoza, Av. Ruiz Leal s/n, Parque General San Martín, CP5500, Mendoza, Argentina
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4
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Mackowetzky K, Dicipulo R, Fox SC, Philibert DA, Todesco H, Doshi JD, Kawakami K, Tierney K, Waskiewicz AJ. Retinoic acid signaling regulates late stages of semicircular canal morphogenesis and otolith maintenance in the zebrafish inner ear. Dev Dyn 2022; 251:1798-1815. [PMID: 35710880 DOI: 10.1002/dvdy.510] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND The vitamin A derivative all-trans retinoic acid (RA) regulates early stages of inner ear development. As the early disruption of the RA pathway results in profound mispatterning of the developing inner ear, this confounds analyses of specific roles in later stages. Therefore, we used the temporal-specific exposure of all-trans RA or diethylaminobenzaldehyde to evaluate RA functions in late otic development. RESULTS Perturbing late RA signaling causes behavioral defects analogous to those expected in larvae suffering from vestibular dysfunction. These larvae also demonstrate malformations of the semi-circular canals, as visualized through (a) use of the transgenic strain nkhspdmc12a, a fluorescent reporter expressed in otic epithelium; and (b) injection of the fluorescent lipophilic dye DiI. We also noted the altered expression of genes encoding ECM proteins or modifying enzymes. Other malformations of the inner ear observed in our work include the loss or reduced size of the utricular and saccular otoliths, suggesting a role for RA in otolith maintenance. CONCLUSION Our work has identified a previously undescribed late phase of RA activity in otic development, demonstrating that vestibular defects observed in human patients in relation to perturbed RA signaling are not solely due to its early disruption in otic development.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Renée Dicipulo
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sabrina C Fox
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Danielle A Philibert
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Hayley Todesco
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jainil D Doshi
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Shizuoka, Japan
| | - Keith Tierney
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew J Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
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5
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Pochat-Cottilloux Y, Martin JE, Jouve S, Perrichon G, Adrien J, Salaviale C, de Muizon C, Cespedes R, Amiot R. The neuroanatomy of Zulmasuchus querejazus (Crocodylomorpha, Sebecidae) and its implications for the paleoecology of sebecosuchians. Anat Rec (Hoboken) 2021; 305:2708-2728. [PMID: 34825786 DOI: 10.1002/ar.24826] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/07/2021] [Accepted: 09/29/2021] [Indexed: 01/14/2023]
Abstract
The endocranial structures of the sebecid crocodylomorph Zulmasuchus querejazus (MHNC 6672) from the Lower Paleocene of Bolivia are described in this article. Using computed tomography scanning, the cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization are reconstructed and compared with those of extant and fossil crocodylomorphs, representative of different ecomorphological adaptations. Z. querejazus exhibits an unusual flexure of the brain, pericerebral spines, semicircular canals with a narrow diameter, as well as enlarged pharyngotympanic sinuses. First, those structures allow to estimate the alert head posture and hearing capabilities of Zulmasuchus. Then, functional comparisons are proposed between this purportedly terrestrial taxon, semi-aquatic, and aquatic forms (extant crocodylians, thalattosuchians, and dyrosaurids). The narrow diameter of the semicircular canals but expanded morphology of the endosseous labyrinths and the enlarged pneumatization of the skull compared to other forms indeed tend to indicate a terrestrial lifestyle for Zulmasuchus. Our results highlight the need to gather new data, especially from altirostral forms in order to further our understanding of the evolution of endocranial structures in crocodylomorphs with different ecomorphological adaptations.
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Affiliation(s)
| | - Jeremy E Martin
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, France
| | - Stéphane Jouve
- Centre de Recherche en Paléontologie - Paris (CR2P), Sorbonne Université, Paris, France
| | | | - Jérome Adrien
- Laboratoire Matériaux, Ingénierie et Science, Institut National des Sciences Appliquées de Lyon, Villeurbanne, France
| | - Céline Salaviale
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, France
| | - Christian de Muizon
- Centre de Recherche en Paléontologie - Paris (CR2P), Muséum National d'Histoire Naturelle, CNRS/MNHN/Sorbonne Université, Paris, France
| | - Ricardo Cespedes
- Museo de Historia Natural 'Alcide D'Orbigny', Cochabamba, Bolivia
| | - Romain Amiot
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, France
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6
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Bhagat R, Bertrand OC, Silcox MT. Evolution of arboreality and fossoriality in squirrels and aplodontid rodents: Insights from the semicircular canals of fossil rodents. J Anat 2021; 238:96-112. [PMID: 32812227 PMCID: PMC7754939 DOI: 10.1111/joa.13296] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 01/03/2023] Open
Abstract
Reconstructing locomotor behaviour for fossil animals is typically done with postcranial elements. However, for species only known from cranial material, locomotor behaviour is difficult to reconstruct. The semicircular canals (SCCs) in the inner ear provide insight into an animal's locomotor agility. A relationship exists between the size of the SCCs relative to body mass and the jerkiness of an animal's locomotion. Additionally, studies have also demonstrated a relationship between SCC orthogonality and angular head velocity. Here, we employ two metrics for reconstructing locomotor agility, radius of curvature dimensions and SCC orthogonality, in a sample of twelve fossil rodents from the families Ischyromyidae, Sciuridae and Aplodontidae. The method utilizing radius of curvature dimensions provided a reconstruction of fossil rodent locomotor behaviour that is more consistent with previous studies assessing fossil rodent locomotor behaviour compared to the method based on SCC orthogonality. Previous work on ischyromyids suggests that this group displayed a variety of locomotor modes. Members of Paramyinae and Ischyromyinae have relatively smaller SCCs and are reconstructed to be relatively slower compared to members of Reithroparamyinae. Early members of the Sciuroidea clade including the sciurid Cedromus wilsoni and the aplodontid Prosciurus relictus are reconstructed to be more agile than ischyromyids, in the range of extant arboreal squirrels. This reconstruction supports previous inferences that arboreality was likely an ancestral trait for this group. Derived members of Sciuridae and Aplodontidae vary in agility scores. The fossil squirrel Protosciurus cf. rachelae is inferred from postcranial material as arboreal, which is in agreement with its high agility, in the range of extant arboreal squirrels. In contrast, the fossil aplodontid Mesogaulus paniensis has a relatively low agility score, similar to the fossorial Aplodontia rufa, the only living aplodontid rodent. This result is in agreement with its postcranial reconstruction as fossorial and with previous indications that early aplodontids were more arboreal than their burrowing descendants.
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Affiliation(s)
- Raj Bhagat
- Department of AnthropologyUniversity of Toronto ScarboroughTorontoONCanada
| | | | - Mary T. Silcox
- Department of AnthropologyUniversity of Toronto ScarboroughTorontoONCanada
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7
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Vestibular Functioning in Children with Neurodevelopmental Disorders Using the Functional Head Impulse Test. Brain Sci 2020; 10:brainsci10110887. [PMID: 33233781 PMCID: PMC7699844 DOI: 10.3390/brainsci10110887] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 01/07/2023] Open
Abstract
Several studies in children with neurodevelopmental disorders (NDDs) including autism spectrum disorders (ASDs), reading impairment, or attention deficit/hyperactive disorder (ADHD) pointed toward a potential dysfunction of the vestibular system, specifically in its complex relationship with the cerebellum. The aim of the present study was to test the functional vestibulo-ocular reflex (VOR) responses in children with NDDs to measure functional performance of the vestibular system. The VOR is specifically involved in this stabilization of the image on the retina during rapid movements of the head. To perform this study, four groups of children with ASD, ADHD, reading impairment, and with neurotypical development (TD) were enrolled (n = 80). We performed the functional head impulse test (fHIT), which measured the percentage of correct responses by asking the child to identify an optotype briefly presented during passive head impulse in each direction of each semicircular canal plane. We observed significantly lower correct answers in children with NDDs compared with those with TD (p < 0.0001). Surprisingly, there was no significant difference between the three groups of children with NDDs. Our study fostered preliminary evidence suggesting altered efficiency of vestibular system in children with NDDs. VOR abnormalities estimated using the fHIT could be used as a proxy of NDD impairments in children, and represent a potential biomarker.
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8
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Spiekman SNF, Neenan JM, Fraser NC, Fernandez V, Rieppel O, Nosotti S, Scheyer TM. The cranial morphology of Tanystropheus hydroides (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography. PeerJ 2020; 8:e10299. [PMID: 33240633 PMCID: PMC7682440 DOI: 10.7717/peerj.10299] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/14/2020] [Indexed: 12/19/2022] Open
Abstract
The postcranial morphology of the extremely long-necked Tanystropheus hydroides is well-known, but observations of skull morphology were previously limited due to compression of the known specimens. Here we provide a detailed description of the skull of PIMUZ T 2790, including a partial endocast and endosseous labyrinth, based on synchrotron microtomographic data, and compare its morphology to that of other early Archosauromorpha. In many features, such as the wide and flattened snout and the configuration of the temporal and palatal regions, Tanystropheus hydroides differs strongly from other early archosauromorphs. The braincase possesses a combination of derived archosaur traits, such as the presence of a laterosphenoid and the ossification of the lateral wall of the braincase, but also differs from archosauriforms in the morphology of the ventral ramus of the opisthotic, the horizontal orientation of the parabasisphenoid, and the absence of a clearly defined crista prootica. Tanystropheus hydroides was a ram-feeder that likely caught its prey through a laterally directed snapping bite. Although the cranial morphology of other archosauromorph lineages is relatively well-represented, the skulls of most tanystropheid taxa remain poorly understood due to compressed and often fragmentary specimens. The recent descriptions of the skulls of Macrocnemus bassanii and now Tanystropheus hydroides reveal a large cranial disparity in the clade, reflecting wide ecological diversity, and highlighting the importance of non-archosauriform Archosauromorpha to both terrestrial and aquatic ecosystems during the Triassic.
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Affiliation(s)
- Stephan N F Spiekman
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
| | | | | | - Vincent Fernandez
- European Synchrotron Radiation Facility, Grenoble, France.,The Natural History Museum, London, UK
| | | | | | - Torsten M Scheyer
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
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9
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Dumont MV, Santucci RM, de Andrade MB, de Oliveira CEM. Paleoneurology of Baurusuchus (Crocodyliformes: Baurusuchidae), ontogenetic variation, brain size, and sensorial implications. Anat Rec (Hoboken) 2020; 305:2670-2694. [PMID: 33211405 DOI: 10.1002/ar.24567] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/18/2020] [Accepted: 10/18/2020] [Indexed: 12/23/2022]
Abstract
Knowledge on crocodyliform paleoneurology has significantly improved with development of computed tomography. However, studies so far have been able to reconstruct brain endocasts based only on single specimens for each taxon. Here for the first time, we reconstructed brain endocasts for multiple fossil specimens of the same crocodyliform taxon (Baurusuchus), consisting of complete skulls of two medium sized specimens, one large adult, and a late juvenile. In addition, we were able to reconstruct the inner ear anatomy of a fragmentary skull using microtomography. We present estimates of brain size using simple models, based on modern Crocodylia, able to adapt brain to endocranial cavity ratios to expected ontogenetic variation instead of using fixed ratios. We also analyzed relative brain sizes, olfactory ratios, facial sensation, alert head posture, best hearing frequencies, and hearing range. The calculated endocranial volumes showed that they can be greatly altered by taphonomic processes, altering both total and partial endocranial volumes. Reconstructed endocasts are compatible with different degrees of occupation along the endocranial cavity and some of their characteristics might be useful as phylogenetic characters. The relative brain size of Baurusuchus seems to be small in comparison to modern crocodilians. Sensorial abilities were somewhat similar to modern crocodilians and hearing ranges and best mean frequencies remarkably similar to modern taxa, whereas olfactory ratio values are a little higher. Differing from its modern relatives, Baurusuchus hypothesized alert head posture is compatible with a terrestrial habit.
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Affiliation(s)
- Marcos V Dumont
- Federal Institute of Brasília, Brasília, Brazil.,University of Brasília, Brasília, Brazil
| | | | - Marco Brandalise de Andrade
- Pontifical Catholic University of Rio Grande do Sul, PUCRS, School of Health and Life Sciences, Porto Alegre, Brazil
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10
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A test of the lateral semicircular canal correlation to head posture, diet and other biological traits in "ungulate" mammals. Sci Rep 2020; 10:19602. [PMID: 33177568 PMCID: PMC7658238 DOI: 10.1038/s41598-020-76757-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/02/2020] [Indexed: 02/08/2023] Open
Abstract
For over a century, researchers have assumed that the plane of the lateral semicircular canal of the inner ear lies parallel to the horizon when the head is at rest, and used this assumption to reconstruct head posture in extinct species. Although this hypothesis has been repeatedly questioned, it has never been tested on a large sample size and at a broad taxonomic scale in mammals. This study presents a comprehensive test of this hypothesis in over one hundred "ungulate" species. Using CT scanning and manual segmentation, the orientation of the skull was reconstructed as if the lateral semicircular canal of the bony labyrinth was aligned horizontally. This reconstructed cranial orientation was statistically compared to the actual head posture of the corresponding species using a dataset of 10,000 photographs and phylogenetic regression analysis. A statistically significant correlation between the reconstructed cranial orientation and head posture is found, although the plane of the lateral semicircular canal departs significantly from horizontal. We thus caution against the use of the lateral semicircular canal as a proxy to infer precisely the horizontal plane on dry skulls and in extinct species. Diet (browsing or grazing) and head-butting behaviour are significantly correlated to the orientation of the lateral semicircular canal, but not to the actual head posture. Head posture and the orientation of the lateral semicircular canal are both strongly correlated with phylogenetic history.
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11
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Schade M, Rauhut OWM, Evers SW. Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory. Sci Rep 2020; 10:9259. [PMID: 32518236 PMCID: PMC7283278 DOI: 10.1038/s41598-020-66261-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/18/2020] [Indexed: 11/18/2022] Open
Abstract
Spinosauridae, a theropod group characterized by elongated snouts, conical teeth, enlarged forelimbs, and often elongated neural spines, show evidence for semiaquatic adaptations and piscivory. It is currently debated if these animals represent terrestrial carnivores with adaptations for a piscivorous diet, or if they largely lived and foraged in aquatic habitats. The holotype of Irritator challengeri, a nearly complete skull from the late Early Cretaceous Santana Formation of northeastern Brazil, includes one of the few preserved spinosaurid braincases and can provide insights into neuroanatomical structures that might be expected to reflect ecological affinities. We generated digital models of the neuroanatomical cavities within the braincase, using computer tomography (CT) data. The cranial endocast of Irritator is generally similar to that of other non-maniraptoriform theropods, with weakly developed distinctions of hindbrain and midbrain features, relatively pronounced cranial flexures and relatively long olfactory tracts. The endosseous labyrinth has a long anterior semicircular canal, a posteriorly inclined common crus and a very large floccular recess fills the area between the semicircular canals. These features indicate that Irritator had the ability for fast and well-controlled pitch-down head movements. The skull table and lateral semicircular canal plane are strongly angled to one another, suggesting a downward angling of approximately 45° of the snout, which reduces interference of the snout with the field of vision of Irritator. These neuroanatomical features are consistent with fast, downward snatching movements in the act of predation, such as are needed for piscivory.
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Affiliation(s)
- Marco Schade
- Institute of Geography and Geology, Palaeontology and Historical Geology, University of Greifswald, 17489, Greifswald, Germany. .,Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.
| | - Oliver W M Rauhut
- Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.,Bayerische Staatssammlung für Paläntologie und Geologie, Staatliche Naturwissenschaftliche Sammlungen Bayerns (SNSB), 80333, München, Germany.,GeoBioCenter, Ludwig-Maximilians-Universität, 80333, München, Germany
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, 17000, Fribourg, Switzerland
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12
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Smith CM, Laitman JT. Alterations to vestibular morphology in highly bred domestic dogs may affect balance. Anat Rec (Hoboken) 2020; 304:116-126. [PMID: 32478937 DOI: 10.1002/ar.24423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/11/2020] [Accepted: 03/24/2020] [Indexed: 12/23/2022]
Abstract
The modern domestic dog (Canis lupus familiaris) provides an excellent model to examine the effects of cranial modification. Extreme variation in skull length among dog breeds due to high levels of selective breeding is known to be linked to disorders of the head and neck. Such alteration may also influence sensory organs including those of the vestibular system (VS), one of the most fundamental sense organs, essential in maintaining balance. Studies in mammals have shown that orientation of ipsilateral semicircular canals (SCCs) of the VS at right angles (orthogonality) is related to angular acceleration sensitivity. Due to their considerable variation in craniofacial form while exhibiting similar locomotion, domestic dogs provide an excellent natural experiment to examine if cranial alteration influences VS functional morphology. Our methods examine how change in cranial base length across dog breeds relates to SCC orthogonality using linear modeling and analyses of variance. The sample studied (29 bony labyrinths of 17 dog breeds) was obtained from a previous study on canid inner ear metrics. Results support the hypothesis that orthogonality between the anterior and posterior SCC + ampulla significantly correlates with cranial base length. This suggests a close relationship between the orientations of SCCs with their ampullae and cranial structure among dog breeds. Specifically, highly derived breeds, such as the brachycephalic pug, have anterior and posterior SCCs and ampullae that deviate the most from orthogonality. Therefore, such highly bred domestic dogs may also have altered vestibular function due to compressed cranial form.
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Affiliation(s)
- Christopher M Smith
- The Graduate Center, City University of New York, New York, New York, USA.,Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,New York Consortium in Evolutionary Primatology, New York, New York, USA
| | - Jeffrey T Laitman
- The Graduate Center, City University of New York, New York, New York, USA.,Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,New York Consortium in Evolutionary Primatology, New York, New York, USA.,Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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13
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Lambert FM, Bacqué-Cazenave J, Le Seach A, Arama J, Courtand G, Tagliabue M, Eskiizmirliler S, Straka H, Beraneck M. Stabilization of Gaze during Early Xenopus Development by Swimming-Related Utricular Signals. Curr Biol 2020; 30:746-753.e4. [PMID: 31956031 DOI: 10.1016/j.cub.2019.12.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/26/2019] [Accepted: 12/13/2019] [Indexed: 01/01/2023]
Abstract
Locomotor maturation requires concurrent gaze stabilization improvement for maintaining visual acuity [1, 2]. The capacity to stabilize gaze, in particular in small aquatic vertebrates where coordinated locomotor activity appears very early, is determined by assembly and functional maturation of inner ear structures and associated sensory-motor circuitries [3-7]. Whereas utriculo-ocular reflexes become functional immediately after hatching [8, 9], semicircular canal-dependent vestibulo-ocular reflexes (VORs) appear later [10]. Thus, small semicircular canals are unable to detect swimming-related head oscillations, despite the fact that corresponding acceleration components are well-suited to trigger an angular VOR [11]. This leaves the utricle as the sole vestibular origin for swimming-related compensatory eye movements [12, 13]. We report a remarkable ontogenetic plasticity of swimming-related head kinematics and vestibular end organ recruitment in Xenopus tadpoles with beneficial consequences for gaze-stabilization. Swimming of older larvae generates sinusoidal head undulations with small, similar curvature angles on the left and right side that optimally activate horizontal semicircular canals. Young larvae swimming causes left-right head undulations with narrow curvatures and strong, bilaterally dissimilar centripetal acceleration components well suited to activate utricular hair cells and to substitute the absent semicircular canal function at this stage. The capacity of utricular signals to supplant semicircular canal function was confirmed by recordings of eye movements and extraocular motoneurons during off-center rotations in control and semicircular canal-deficient tadpoles. Strong alternating curvature angles and thus linear acceleration profiles during swimming in young larvae therefore represents a technically elegant solution to compensate for the incapacity of small semicircular canals to detect angular acceleration components.
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Affiliation(s)
| | | | - Anne Le Seach
- Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Université de Paris, F-75270 Paris, France
| | - Jessica Arama
- Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Université de Paris, F-75270 Paris, France
| | - Gilles Courtand
- INCIA, CNRS UMR 5287, Université de Bordeaux, F-33076 Bordeaux, France
| | - Michele Tagliabue
- Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Université de Paris, F-75270 Paris, France
| | - Selim Eskiizmirliler
- Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Université de Paris, F-75270 Paris, France
| | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, Grosshaderner Str. 2, 82152 Planegg, Germany
| | - Mathieu Beraneck
- Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Université de Paris, F-75270 Paris, France.
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14
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Cerio DG, Witmer LM. Intraspecific variation and symmetry of the inner-ear labyrinth in a population of wild turkeys: implications for paleontological reconstructions. PeerJ 2019; 7:e7355. [PMID: 31372322 PMCID: PMC6659666 DOI: 10.7717/peerj.7355] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/26/2019] [Indexed: 12/25/2022] Open
Abstract
The cochlea and semicircular canals (SCCs) of the inner ear are vital neurosensory devices. There are associations between the anatomy of these sensorineural structures, their function, and the function of related biological systems, for example, hearing ability, gaze stabilization, locomotor agility, and posture. The endosseous labyrinth is frequently used as a proxy to infer the performance of the hearing and vestibular systems, locomotor abilities, and ecology of extinct species. Such fossil inferences are often based on single specimens or even a single ear, representing an entire species. To address whether a single ear is representative of a population, we used geometric morphometrics to quantitatively assess the variation in shape and symmetry in a sample of endosseous labyrinths of wild turkeys Meleagris gallopavo of southern Ohio. We predicted that ears would be symmetrical both within individuals and across the sample; that labyrinth shape and size would covary; that labyrinth shape would vary with the size of the brain, measured as width of the endocranium at the cerebellum; and that labyrinths would be morphologically integrated. To test these predictions, we microCT-scanned the heads of 26 cadaveric turkeys, digitally segmented their endosseous labyrinths in Avizo, and assigned 15 manual landmarks and 20 sliding semilandmarks to each digital model. Following Procrustes alignment, we conducted an analysis of bilateral symmetry, a Procrustes regression analysis for allometry and other covariates including side and replicate, and analyses of global integration and modularity. Based on Procrustes distances, no individual’s left and right ears were clearly different from each other. When comparing the ears of different specimens, statistically clear differences in shape were found in only 66 of more than 1,300 contrasts. Moreover, effects of both directional and fluctuating asymmetry were very small—generally, two orders of magnitude smaller than the variance explained by individual variation. Statistical tests disagreed on whether these asymmetric effects crossed the threshold of significance, possibly due to non-isotropic variation among landmarks. Regardless, labyrinths appeared to primarily vary in shape symmetrically. Neither labyrinth size nor endocranial width was correlated with labyrinth shape, contrary to our expectations. Finally, labyrinths were found to be moderately integrated in a global sense, but four weakly separated modules—the three SCCs and cochlea—were recovered using a maximum-likelihood analysis. The results show that both fluctuating and directional asymmetry play a larger role in shape variation than expected—but nonetheless, endosseous labyrinths are symmetrical within individuals and at the level of the population, and their shape varies symmetrically. Thus, inferences about populations, and very possibly species, may be confidently made when only a single specimen, or even a single ear, is available for study.
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Affiliation(s)
- Donald G Cerio
- Department of Biological Sciences, Ohio University, Athens, OH, USA.,Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
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15
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Khan SI, Della Santina CC, Migliaccio AA. Angular vestibuloocular reflex responses in Otop1 mice. II. Otolith sensor input improves compensation after unilateral labyrinthectomy. J Neurophysiol 2019; 121:2300-2307. [DOI: 10.1152/jn.00812.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The role of the otoliths in mammals in the normal angular vestibuloocular reflex (VOR) was characterized in an accompanying study based on the Otopetrin1 (Otop1) mouse, which lacks functioning otoliths because of failure to develop otoconia but seems to have otherwise normal peripheral anatomy and neural circuitry. That study showed that otoliths do not contribute to the normal horizontal (rotation about Earth-vertical axis parallel to dorso-ventral axis) and vertical (rotation about Earth-vertical axis parallel to interaural axis) angular VOR but do affect gravity context-specific VOR adaptation. By using these animals, we sought to determine whether the otoliths play a role in the angular VOR after unilateral labyrinthectomy when the total canal signal is reduced. In five Otop1 mice and five control littermates we measured horizontal and vertical left-ear-down and right-ear-down sinusoidal VOR (0.2–10 Hz, 20–100°/s) during the early (3–5 days) and plateau (28–32 days) phases of compensation after unilateral labyrinthectomy and compared these measurements with baseline preoperative responses from the accompanying study. From similar baselines, acute gain loss was ~25% less in control mice, and chronic gain recovery was ~40% more in control mice. The acute data suggest that the otoliths contribute to the angular VOR when there is a loss of canal function. The chronic data suggest that a unilateral otolith signal can significantly improve angular VOR compensation. These data have implications for vestibular rehabilitation of patients with both canal and otolith loss and the development of vestibular implants, which currently only mimic the canals on one side.NEW & NOTEWORTHY This is the first study examining the role of the otoliths (defined here as the utricle and saccule) on the acute and chronic angular vestibuloocular reflex (VOR) after unilateral labyrinthectomy in an animal model in which the otoliths are reliably inactivated and the semicircular canals preserved. This study shows that the otolith signal is used to augment the acute angular VOR and help boost VOR compensation after peripheral injury.
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Affiliation(s)
- Serajul I. Khan
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Charles C. Della Santina
- Department of Otolaryngology—Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland
| | - Americo A. Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
- Department of Otolaryngology—Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland
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16
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Vasilopoulou-Kampitsi M, Goyens J, Van Damme R, Aerts P. The ecological signal on the shape of the lacertid vestibular system: simple versus complex microhabitats. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- M Vasilopoulou-Kampitsi
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - J Goyens
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - R Van Damme
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - P Aerts
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Antwerp, Belgium
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
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17
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Rabbitt RD. Semicircular canal biomechanics in health and disease. J Neurophysiol 2019; 121:732-755. [PMID: 30565972 PMCID: PMC6520623 DOI: 10.1152/jn.00708.2018] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
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Affiliation(s)
- R. D. Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
- Otolaryngology-Head Neck Surgery, University of Utah, Salt Lake City, Utah
- Neuroscience Program, University of Utah, Salt Lake City, Utah
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18
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Schwab JA, Kriwet J, Weber GW, Pfaff C. Carnivoran hunting style and phylogeny reflected in bony labyrinth morphometry. Sci Rep 2019; 9:70. [PMID: 30635617 PMCID: PMC6329752 DOI: 10.1038/s41598-018-37106-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/30/2018] [Indexed: 11/09/2022] Open
Abstract
Carnivorans are a highly diverse and successful group of mammals, found on the top of the food chain. They originated in the Palaeocene (ca. 60 Ma) and have developed numerous lifestyles, locomotion modes and hunting strategies during their evolutionary history. Mechanosensory organs, such as the inner ear (which houses senses of equilibrium and hearing), represent informative anatomical systems to obtain insights into function, ecology and phylogeny of extant and extinct vertebrates. Using µCT scans, we examined bony labyrinths of a broad sample of various carnivoran species, to obtain new information about hunting behaviours of ancient carnivorans. Bony labyrinths were digitally reconstructed and measurements were taken directly from these 3D models. Principal component analyses generally separated various hunting strategies (pursuit, pounce, ambush and occasional), but also support their phylogenetic relationships (Canoidea vs. Feloidea). The height, width and length of all three semicircular canals show functional morphological adaptations, whereas the diameter of the canals, the height of the cochlea and particularly the angle between the lateral semicircular canal and the cochlea indicate a phylogenetic signal. The results demonstrate that the bony labyrinth provides a powerful ecological proxy reflecting both predatory habits as well as phylogenetic relationships in extinct and extant carnivorans.
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Affiliation(s)
- Julia A Schwab
- Department of Palaeontology, Faculty of Earth Science, Geography and Astronomy, University of Vienna, Geozentrum, Althanstraße 14, 1090, Vienna, Austria. .,School of GeoSciences, Grant Institute, University of Edinburgh, The King's Buildings, James Hutton Road, Edinburgh, EH9 3JW, UK.
| | - Jürgen Kriwet
- Department of Palaeontology, Faculty of Earth Science, Geography and Astronomy, University of Vienna, Geozentrum, Althanstraße 14, 1090, Vienna, Austria
| | - Gerhard W Weber
- Department of Anthropology & Core Facility for Micro-Computed Tomography, Faculty of Life Science, University of Vienna, Althanstraße 14, 1090, Vienna, Austria
| | - Cathrin Pfaff
- Department of Palaeontology, Faculty of Earth Science, Geography and Astronomy, University of Vienna, Geozentrum, Althanstraße 14, 1090, Vienna, Austria
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19
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von Baczko MB, Taborda JRA, Desojo JB. Paleoneuroanatomy of the aetosaur Neoaetosauroides engaeus (Archosauria: Pseudosuchia) and its paleobiological implications among archosauriforms. PeerJ 2018; 6:e5456. [PMID: 30155359 PMCID: PMC6109373 DOI: 10.7717/peerj.5456] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/26/2018] [Indexed: 01/25/2023] Open
Abstract
The paleoneuroanatomy of pseudosuchian archosaurs is poorly known, based on direct examination of the internal morphology of braincases and a few artificial endocasts. Among aetosaurs, only one endocast has been described almost a century ago by Case (1921) corresponding to Desmatosuchus spurensis from the Chinle Formation (Norian) of Texas, US, based on a resin cast. Here, we describe the first natural endocast of an aetosaur, Neoaetosauroides engaeus from the Los Colorados Formation (Norian) of NW Argentina, and also developed the first digital endocast of this taxon including the encephalon, cranial nerves, inner ear, and middle ear sinuses. The neuroanatomy of Neoaetosauroides engaeus exhibits several differences from that of Desmatosuchus spurensis despite their phylogenetic proximity, which may be a reflection of their different habits. The information provided by the endocasts of Neoaetosauroides engaeus about its olfactory region and the orientation of its head, based on the inclination of the inner ear, could support the proposal for an animalivorous diet, instead of an herbivorous one as in most aetosaurs. The new information here obtained contributes to the knowledge of the neuroanatomical diversity of archosauriforms and more specifically among pseudosuchians and their paleobiological roles in the Triassic continental communities.
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Affiliation(s)
- M Belen von Baczko
- División Paleontología de Vertebrados, Museo de La Plata, La Plata, Argentina.,Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Jeremías R A Taborda
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Universidad Nacional de Córdoba - CONICET, Córdoba, Argentina
| | - Julia Brenda Desojo
- División Paleontología de Vertebrados, Museo de La Plata, La Plata, Argentina.,Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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20
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Benson RBJ, Starmer-Jones E, Close RA, Walsh SA. Comparative analysis of vestibular ecomorphology in birds. J Anat 2018; 231:990-1018. [PMID: 29156494 DOI: 10.1111/joa.12726] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2017] [Indexed: 02/06/2023] Open
Abstract
The bony labyrinth of vertebrates houses the semicircular canals. These sense rotational accelerations of the head and play an essential role in gaze stabilisation during locomotion. The sizes and shapes of the semicircular canals have hypothesised relationships to agility and locomotory modes in many groups, including birds, and a burgeoning palaeontological literature seeks to make ecological interpretations from the morphology of the labyrinth in extinct species. Rigorous tests of form-function relationships for the vestibular system are required to support these interpretations. We test the hypothesis that the lengths, streamlines and angles between the semicircular canals are related to body size, wing kinematics and flying style in birds. To do this, we applied geometric morphometrics and multivariate phylogenetic comparative methods to a dataset of 64 three-dimensional reconstructions of the endosseous labyrinth obtained using micro-computed tomography scanning of bird crania. A strong relationship between centroid size of the semicircular canals and body size indicates that larger birds have longer semicircular canals compared with their evolutionary relatives. Wing kinematics related to manoeuvrability (and quantified using the brachial index) explain a small additional portion of the variance in labyrinth size. We also find strong evidence for allometric shape change in the semicircular canals of birds, indicating that major aspects of the shape of the avian labyrinth are determined by spatial constraints. The avian braincase accommodates a large brain, a large eye and large semicircular canals compared with other tetrapods. Negative allometry of these structures means that the restriction of space within the braincase is intense in small birds. This may explain our observation that the angles between planes of the semicircular canals of birds deviate more strongly from orthogonality than those of mammals, and especially from agile, gliding and flying mammals. Furthermore, we find little support for relationships between labyrinth shape and flying style or wing kinematics. Overall, our results suggest that the topological problem of fitting long semicircular canals into a spatially constrained braincase is more important in determining the shape of the avian labyrinth than the specifics of locomotory style or agility. Our results tentatively indicate a link between visual acuity and proportional size of the labyrinth among birds. This suggests that the large labyrinths of birds compared with other tetrapods may result from their generally high visual acuities, and not directly from their ability to fly. The endosseous labyrinths of extinct birds and their close dinosaurian relatives may allow broad inferences about flight or vision, but so far provide few specific insights into detailed aspects of locomotion.
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Affiliation(s)
| | | | - Roger A Close
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Stig A Walsh
- Department of Natural Sciences, National Museums Scotland, Edinburgh, UK.,School of GeoSciences, The King's Buildings, Edinburgh, UK
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21
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Belli HM, Bresee CS, Graff MM, Hartmann MJZ. Quantifying the three-dimensional facial morphology of the laboratory rat with a focus on the vibrissae. PLoS One 2018; 13:e0194981. [PMID: 29621356 PMCID: PMC5886528 DOI: 10.1371/journal.pone.0194981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/14/2018] [Indexed: 11/24/2022] Open
Abstract
The morphology of an animal's face will have large effects on the sensory information it can acquire. Here we quantify the arrangement of cranial sensory structures of the rat, with special emphasis on the mystacial vibrissae (whiskers). Nearly all mammals have vibrissae, which are generally arranged in rows and columns across the face. The vibrissae serve a wide variety of important behavioral functions, including navigation, climbing, wake following, anemotaxis, and social interactions. To date, however, there are few studies that compare the morphology of vibrissal arrays across species, or that describe the arrangement of the vibrissae relative to other facial sensory structures. The few studies that do exist have exploited the whiskers' grid-like arrangement to quantify array morphology in terms of row and column identity. However, relying on whisker identity poses a challenge for comparative research because different species have different numbers and arrangements of whiskers. The present work introduces an approach to quantify vibrissal array morphology regardless of the number of rows and columns, and to quantify the array's location relative to other sensory structures. We use the three-dimensional locations of the whisker basepoints as fundamental parameters to generate equations describing the length, curvature, and orientation of each whisker. Results show that in the rat, whisker length varies exponentially across the array, and that a hard limit on intrinsic curvature constrains the whisker height-to-length ratio. Whiskers are oriented to "fan out" approximately equally in dorsal-ventral and rostral-caudal directions. Quantifying positions of the other sensory structures relative to the whisker basepoints shows remarkable alignment to the somatosensory cortical homunculus, an alignment that would not occur for other choices of coordinate systems (e.g., centered on the midpoint of the eyes). We anticipate that the quantification of facial sensory structures, including the vibrissae, will ultimately enable cross-species comparisons of multi-modal sensing volumes.
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Affiliation(s)
- Hayley M. Belli
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Chris S. Bresee
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, Illinois, United States of America
| | - Matthew M. Graff
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Mitra J. Z. Hartmann
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America
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22
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Size Variation under Domestication: Conservatism in the inner ear shape of wolves, dogs and dingoes. Sci Rep 2017; 7:13330. [PMID: 29042574 PMCID: PMC5645459 DOI: 10.1038/s41598-017-13523-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/25/2017] [Indexed: 11/08/2022] Open
Abstract
A broad sample of wolves, dingoes, and domesticated dogs of different kinds and time periods was used to identify changes in size and shape of the organs of balance and hearing related to domestication and to evaluate the potential utility of uncovered patterns as markers of domestication. Using geometric morphometrics coupled with non-invasive imaging and three-dimensional reconstructions, we exposed and compared complex structures that remain largely conserved. There is no statistically significant difference in the levels of shape variation between prehistoric and modern dogs. Shape variance is slightly higher for the different components of the inner ear in modern dogs than in wolves, but these differences are not significant. Wolves express a significantly greater level of variance in the angle between the lateral and the posterior canal than domestic dog breeds. Wolves have smaller levels of size variation than dogs. In terms of the shape of the semicircular canals, dingoes reflect the mean shape in the context of variation in the sample. This mirrors the condition of feral forms in other organs, in which there is an incomplete return to the characteristics of the ancestor. In general, morphological diversity or disparity in the inner ear is generated by scaling.
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23
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Dickson BV, Sherratt E, Losos JB, Pierce SE. Semicircular canals in Anolis lizards: ecomorphological convergence and ecomorph affinities of fossil species. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170058. [PMID: 29134056 PMCID: PMC5666239 DOI: 10.1098/rsos.170058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
Anolis lizards are a model system for the study of adaptive radiation and convergent evolution. Greater Antillean anoles have repeatedly evolved six similar forms or ecomorphs: crown-giant, grass-bush, twig, trunk, trunk-crown and trunk-ground. Members of each ecomorph category possess a specific set of morphological, ecological and behavioural characteristics which have been acquired convergently. Here we test whether the semicircular canal system-the organ of balance during movement-is also convergent among ecomorphs, reflecting the shared sensory requirements of their ecological niches. As semicircular canal shape has been shown to reflect different locomotor strategies, we hypothesized that each Anolis ecomorph would have a unique canal morphology. Using three-dimensional semilandmarks and geometric morphometrics, semicircular canal shape was characterized in 41 Anolis species from the Greater Antilles and the relationship between canal shape and ecomorph grouping, phylogenetic history, size, head dimensions, and perch characteristics was assessed. Further, canal morphology of modern species was used to predict the ecomorph affinity of five fossil anoles from the Miocene of the Dominican Republic. Of the covariates tested, our study recovered ecomorph as the single-most important covariate of canal morphology in modern taxa; although phylogenetic history, size, and head dimensions also showed a small, yet significant correlation with shape. Surprisingly, perch characteristics were not found to be significant covariates of canal shape, even though they are important habitat variables. Using posterior probabilities, we found that the fossil anoles have different semicircular canals shapes to modern ecomorph groupings implying extinct anoles may have been interacting with their Miocene environment in different ways to modern Anolis species.
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Affiliation(s)
- Blake V. Dickson
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Emma Sherratt
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Jonathan B. Losos
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Stephanie E. Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
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24
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Schellhorn R. A potential link between lateral semicircular canal orientation, head posture, and dietary habits in extant rhinos (Perissodactyla, Rhinocerotidae). J Morphol 2017; 279:50-61. [DOI: 10.1002/jmor.20753] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 08/18/2017] [Accepted: 08/26/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Rico Schellhorn
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8; Bonn 53115 Germany
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25
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Coutier F, Hautier L, Cornette R, Amson E, Billet G. Orientation of the lateral semicircular canal in Xenarthra and its links with head posture and phylogeny. J Morphol 2017; 278:704-717. [PMID: 28185320 DOI: 10.1002/jmor.20665] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/10/2017] [Accepted: 01/23/2017] [Indexed: 02/06/2023]
Abstract
The orientation of the semicircular canals of the inner ear in the skull of vertebrates is one of the determinants of the capacity of this system to detect a given rotational movement of the head. Past functional studies on the spatial orientation of the semicircular canals essentially focused on the lateral semicircular canal (LSC), which is supposedly held close to horizontal during rest and/or alert behaviors. However, they generally investigated this feature in only a few and distantly related taxa. Based on 3D-models reconstructed from µCT-scans of skulls, we examined the diversity of orientations of the LSC within one of the four major clades of placental mammals, that is, the superorder Xenarthra, with a data set that includes almost all extant genera and two extinct taxa. We observed a wide diversity of LSC orientations relative to the basicranium at both intraspecific and interspecific scales. The estimated phylogenetic imprint on the orientation of the LSC was significant but rather low within the superorder, though some phylogenetic conservatism was detected for armadillos that were characterized by a strongly tilted LSC. A convergence between extant suspensory sloths was also detected, both genera showing a weakly tilted LSC. Our preliminary analysis of usual head posture in extant xenarthrans based on photographs of living animals further revealed that the LSC orientation in armadillos is congruent with a strongly nose-down head posture. It also portrayed a more complex situation for sloths and anteaters. Finally, we also demonstrate that the conformation of the cranial vault and nuchal crests as well as the orientation of the posterior part of the petrosal may covary with the LSC orientation in Xenarthra. Possible inferences for the head postures of extinct xenarthrans such as giant ground sloths are discussed in the light of these results.
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Affiliation(s)
- Florence Coutier
- Department of Origines et évolution, Sorbonne Universités, CR2P, UMR CNRS 7207, Univ Paris 06, Muséum national d'Histoire naturelle, 8 rue Buffon, Paris, 75005, France
| | - Lionel Hautier
- Department of Forme, Institut des Sciences de l'Evolution de Montpellier, Université Montpellier, CNRS, IRD, EPHE, Cc 064; place Eugène Bataillon, Montpellier Cedex 5, 34095, France
| | - Raphaël Cornette
- Department of Origines et évolution, Institut de Systématique, Évolution, Biodiversité (ISYEB) - UMR 7205 - CNRS, MNHN, UPMC, EPHE- Muséum national d'Histoire naturelle - Sorbonne Universités, 57 rue Cuvier, CP 30, 75005, Paris, France
| | - Eli Amson
- Humboldt-Universität, AG Morphologie und Formengeschichte, Bild Wissen Gestaltung - ein interdisziplinäres Labor & Institut für Biologie, Philippstraße, 12/13, Berlin, D-10115, Germany
| | - Guillaume Billet
- Department of Origines et évolution, Sorbonne Universités, CR2P, UMR CNRS 7207, Univ Paris 06, Muséum national d'Histoire naturelle, 8 rue Buffon, Paris, 75005, France
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Effect of Spatial Orientation of the Horizontal Semicircular Canal on the Vestibulo-Ocular Reflex. Otol Neurotol 2016; 38:239-243. [PMID: 27898608 DOI: 10.1097/mao.0000000000001291] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine if an alignment of the horizontal semi-circular canal (hSCC) with the plane of rotation would enhance the vestibular-ocular reflex (VOR) gain result as it has been previously suggested. STUDY DESIGN Comparative study of a physiological vestibular function test in healthy subjects. SETTING Tertiary referral center for otology and neurotology. PATIENTS Twenty two healthy volunteers were recruited for this study. Their mean age was 25.6 years and the sex distribution was 14:8 (M:F). None of the subjects had a history of audiovestibular disorders. INTERVENTION The video Head Impulse Test (v-HIT) was performed with the hSCC in the conventional position (head upright, horizontal gaze) and also with the hSCC in-line with the earth horizontal. MAIN OUTCOME MEASURES depending on the alignment of the hSCC with the plane of head rotation. RESULTS There was no significant difference between the results, either for the VOR gain at 60 ms, or the regression slope gain, when the two alternative head positions were compared. CONCLUSIONS The data acquired in this study show that the VOR as measured by the v-HIT is not enhanced by aligning the plane of the hSCC with the plane of rotation during the testing procedure. Hence, we recommend that the positioning of the patient, with the head upright and a horizontal gaze direction should be routinely used in the clinical evaluation of the angular VOR by v-HIT.
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Forasiepi AM, MacPhee RDE, Del Pino SH, Schmidt GI, Amson E, Grohé C. Exceptional Skull of Huayqueriana (Mammalia, Litopterna, Macraucheniidae) From the Late Miocene of Argentina: Anatomy, Systematics, and Paleobiological Implications. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2016. [DOI: 10.1206/0003-0090-404.1.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Giles S, Rogers M, Friedman M. Bony labyrinth morphology in early neopterygian fishes (Actinopterygii: Neopterygii). J Morphol 2016; 279:426-440. [PMID: 27165962 DOI: 10.1002/jmor.20551] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 11/09/2022]
Abstract
Endocasts of the osseous labyrinth have the potential to yield information about both phylogenetic relationships and ecology. Although bony labyrinth morphology is well documented in many groups of fossil vertebrates, little is known for early Neopterygii, the major fish radiation containing living teleosts, gars and the bowfin. Here, we reconstruct endocasts of the bony labyrinth and associated structures for a sample of Mesozoic neopterygian fishes using high-resolution computed tomography. Our sample includes taxa unambiguously assigned to either the teleost (Dorsetichthys, "Pholidophorus," Elopoides) and holostean ("Aspidorynchus," "Caturus," Heterolepidotus) total-groups, as well as examples of less certain phylogenetic position (an unnamed parasemionotid and Dapedium). Our models provide a test of anatomical interpretations for forms where bony labyrinths were reconstructed based on destructive tomography ("Caturus") or inspection of the lateral wall of the cranial chamber (Dorsetichthys), and deliver the first detailed insights on inner ear morphology in the remaining taxa. With respect to relationships, traits apparent in the bony labyrinth and associated structures broadly support past phylogenetic hypotheses concerning taxa agreed to have reasonably secure systematic placements. Inner ear morphology supports placement of Dapedium with holosteans rather than teleosts, while preserved structure in the unnamed parasemionotid is generalized to the degree that it provides no evidence of close affinity with either of the crown neopterygian lineages. This study provides proof-of-concept for the systematic utility of the inner ear in neopterygians that, in combination with similar findings for earlier-diverging actinopterygian lineages, points to the substantial potential of this anatomical system for addressing the longstanding questions in the relationships of fossil ray-finned fishes to one another and living groups. J. Morphol. 279:426-440, 2018. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sam Giles
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
| | - Molly Rogers
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK
| | - Matt Friedman
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
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Straka H, Zwergal A, Cullen KE. Vestibular animal models: contributions to understanding physiology and disease. J Neurol 2016; 263 Suppl 1:S10-23. [PMID: 27083880 PMCID: PMC4833800 DOI: 10.1007/s00415-015-7909-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/11/2015] [Accepted: 09/12/2015] [Indexed: 12/20/2022]
Abstract
Our knowledge of the vestibular sensory system, its functional significance for gaze and posture stabilization, and its capability to ensure accurate spatial orientation perception and spatial navigation has greatly benefitted from experimental approaches using a variety of vertebrate species. This review summarizes the attempts to establish the roles of semicircular canal and otolith endorgans in these functions followed by an overview of the most relevant fields of vestibular research including major findings that have advanced our understanding of how this system exerts its influence on reflexive and cognitive challenges encountered during daily life. In particular, we highlight the contributions of different animal models and the advantage of using a comparative research approach. Cross-species comparisons have established that the morpho-physiological properties underlying vestibular signal processing are evolutionarily inherent, thereby disclosing general principles. Based on the documented success of this approach, we suggest that future research employing a balanced spectrum of standard animal models such as fish/frog, mouse and primate will optimize our progress in understanding vestibular processing in health and disease. Moreover, we propose that this should be further supplemented by research employing more “exotic” species that offer unique experimental access and/or have specific vestibular adaptations due to unusual locomotor capabilities or lifestyles. Taken together this strategy will expedite our understanding of the basic principles underlying vestibular computations to reveal relevant translational aspects. Accordingly, studies employing animal models are indispensible and even mandatory for the development of new treatments, medication and technical aids (implants) for patients with vestibular pathologies.
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Affiliation(s)
- Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, Grosshaderner Str. 2, 82152, Planegg, Germany. .,German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University of Munich, Munich, Germany.
| | - Andreas Zwergal
- German Center for Vertigo and Balance Disorders, DSGZ, Ludwig-Maximilians-University of Munich, Munich, Germany.,Department of Neurology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, QC, H3A 0G4, Canada
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Perier A, Lebrun R, Marivaux L. Different Level of Intraspecific Variation of the Bony Labyrinth Morphology in Slow- Versus Fast-Moving Primates. J MAMM EVOL 2016. [DOI: 10.1007/s10914-016-9323-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Cuthbertson RS, Maddin HC, Holmes RB, Anderson JS. The Braincase and Endosseous Labyrinth of Plioplatecarpus peckensis (Mosasauridae, Plioplatecarpinae), With Functional Implications for Locomotor Behavior. Anat Rec (Hoboken) 2015; 298:1597-611. [PMID: 26052684 DOI: 10.1002/ar.23180] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 04/06/2015] [Accepted: 04/07/2015] [Indexed: 11/06/2022]
Abstract
Adaptations of mosasaurs to the aquatic realm have been extensively studied from the perspective of modifications to the post-cranial skeleton. In recent years, imaging techniques such as computed tomography have permitted the acquisition of anatomical data from previously inaccessible sources. An exquisitely preserved specimen of the plioplatecarpine mosasaur Plioplatecarpus peckensis presents an opportunity to examine the detailed structure of the braincase, as well as the form of the otic capsule endocast. These data elaborate upon previous descriptions of the braincase of Plioplatecarpus, and provide a detailed, three dimensional reconstruction of the osseous labyrinth for the first time. The otic capsule endocasts reveal that the size of the labyrinth relative to head size is comparable to that of other squamates, suggesting that labyrinth size was not a factor in increasing sensitivity. However, all three semicircular canals are tall and strongly arced to a degree comparable to, and even exceeding, that observed in arboreal and aquatic lizards. Comparison of the sensitivity of the canals in each of the three major axes of rotation suggests Plioplatecarpus peckensis may have been most sensitive to movements in the pitch axis. Although early mosasaurs were probably anguilliform swimmers, most are thought to have been subcarangiform to thunniform locomotors with a near-rigid body form and likely decreased maneuverability. The data from the labyrinth presented here add a potential new dimension to this model of locomotion for further consideration, wherein changes in orientation, such as pitch, may have been more common locomotor behaviors than previously thought.
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Affiliation(s)
- Robin S Cuthbertson
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada, T2N 1N4
| | - Hillary C Maddin
- Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada, K1S 5B6
| | - Robert B Holmes
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9
| | - Jason S Anderson
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
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Schutz H, Jamniczky HA, Hallgrímsson B, Garland T. Shape-shift: semicircular canal morphology responds to selective breeding for increased locomotor activity. Evolution 2014; 68:3184-98. [PMID: 25130322 DOI: 10.1111/evo.12501] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 07/06/2014] [Indexed: 02/05/2023]
Abstract
Variation in semicircular canal morphology correlates with locomotor agility among species of mammals. An experimental evolutionary mouse model was used to test the hypotheses that semicircular canal morphology (1) evolves in response to selective breeding for increased locomotor activity, (2) exhibits phenotypic plasticity in response to early-onset chronic exercise, and (3) is unique in individuals possessing the minimuscle phenotype. We examined responses in canal morphology to prolonged wheel access and selection in laboratory mice from four replicate lines bred for high voluntary wheel-running (HR) and four nonselected control (C) lines. Linear measurements and a suite of 3D landmarks were obtained from 3D reconstructions of μCT-scanned mouse crania (μCT is microcomputed tomography). Body mass was smaller in HR than C mice and was a significant predictor of both radius of curvature and 3D canal shape. Controlling for body mass, radius of curvature did not differ statistically between HR and C mice, but semicircular canal shape did. Neither chronic wheel access nor minimuscle affected radius of curvature or canal shape These findings suggest that semicircular canal morphology is responsive to evolutionary changes in locomotor behavior, but the pattern of response is potentially different in small- versus large-bodied species.
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Affiliation(s)
- Heidi Schutz
- Biology Department, Pacific Lutheran University, Tacoma, Washington, 98477; Department of Biology, University of California, Riverside, California, 92521.
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Functional implications of ubiquitous semicircular canal non-orthogonality in mammals. PLoS One 2013; 8:e79585. [PMID: 24260256 PMCID: PMC3834179 DOI: 10.1371/journal.pone.0079585] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 10/02/2013] [Indexed: 12/20/2022] Open
Abstract
The 'canonical model' of semicircular canal orientation in mammals assumes that 1) the three ipsilateral canals of an inner ear exist in orthogonal planes (i.e., orthogonality), 2) corresponding left and right canal pairs have equivalent angles (i.e., angle symmetry), and 3) contralateral synergistic canals occupy parallel planes (i.e., coplanarity). However, descriptions of vestibular anatomy that quantify semicircular canal orientation in single species often diverge substantially from this model. Data for primates further suggest that semicircular canal orthogonality varies predictably with the angular head velocities encountered in locomotion. These observations raise the possibility that orthogonality, symmetry, and coplanarity are misleading descriptors of semicircular canal orientation in mammals, and that deviations from these norms could have significant functional consequences. Here we critically assess the canonical model of semicircular canal orientation using high-resolution X-ray computed tomography scans of 39 mammal species. We find that substantial deviations from orthogonality, angle symmetry, and coplanarity are the rule for the mammals in our comparative sample. Furthermore, the degree to which the semicircular canals of a given species deviate from orthogonality is negatively correlated with estimated vestibular sensitivity. We conclude that the available comparative morphometric data do not support the canonical model and that its overemphasis as a heuristic generalization obscures a large amount of functionally relevant variation in semicircular canal orientation between species.
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Benoit J, Essid EM, Marzougui W, Khayati Ammar H, Lebrun R, Tabuce R, Marivaux L. New insights into the ear region anatomy and cranial blood supply of advanced stem Strepsirhini: evidence from three primate petrosals from the Eocene of Chambi, Tunisia. J Hum Evol 2013; 65:551-72. [PMID: 23938180 DOI: 10.1016/j.jhevol.2013.06.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 05/16/2013] [Accepted: 06/26/2013] [Indexed: 01/29/2023]
Abstract
We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs.
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Affiliation(s)
- Julien Benoit
- Laboratoire de Paléontologie, Institut des Sciences de l'Évolution de Montpellier (ISE-M, UMR-CNRS 5554), c.c. 064, Université Montpellier 2, place Eugène Bataillon, F-34095 Montpellier Cedex 05, France.
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Wu C, Yang L, Hua C, Wang K, Zhang T, Dai P. Geometrical and volume changes of the membranous vestibular labyrinth in guinea pigs with endolymphatic hydrops. ORL J Otorhinolaryngol Relat Spec 2013; 75:108-16. [PMID: 23817074 DOI: 10.1159/000350569] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 03/06/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To evaluate geometrical and volume changes of membranous vestibular labyrinths in guinea pigs after endolymphatic hydrops (EH). METHODS The membranous labyrinths of normal guinea pigs and of those with EH for 4 and 8 weeks were reconstructed after being scanned using micro-computed tomography subseqent to being stained in osmium tetroxide (OsO4). The diameters and volumes of the semicircular ducts, ampullae, utricles and saccules were measured based on the three-dimensional models. RESULTS The diameters of the ampullae and utricles of EH guinea pigs were greater than those of the normal guinea pigs, while there were no significant differences in the diameters of the semicircular ducts among all groups. The volumes of ampullae, utricles and saccules of the EH groups were greater than those of the control group, but there were no changes in volumes of semicircular ducts after EH. CONCLUSION The dilations of the membranous vestibular labyrinth in guinea pigs with EH mainly occur at the ampullae, utricles and saccules.
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Affiliation(s)
- Caiqin Wu
- Eye & ENT Hospital, Fudan University, Shanghai, China
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Ekdale EG. Comparative Anatomy of the Bony Labyrinth (Inner Ear) of Placental Mammals. PLoS One 2013; 8:e66624. [PMID: 23805251 PMCID: PMC3689836 DOI: 10.1371/journal.pone.0066624] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 05/07/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Variation is a naturally occurring phenomenon that is observable at all levels of morphology, from anatomical variations of DNA molecules to gross variations between whole organisms. The structure of the otic region is no exception. The present paper documents the broad morphological diversity exhibited by the inner ear region of placental mammals using digital endocasts constructed from high-resolution X-ray computed tomography (CT). Descriptions cover the major placental clades, and linear, angular, and volumetric dimensions are reported. PRINCIPAL FINDINGS The size of the labyrinth is correlated to the overall body mass of individuals, such that large bodied mammals have absolutely larger labyrinths. The ratio between the average arc radius of curvature of the three semicircular canals and body mass of aquatic species is substantially lower than the ratios of related terrestrial taxa, and the volume percentage of the vestibular apparatus of aquatic mammals tends to be less than that calculated for terrestrial species. Aspects of the bony labyrinth are phylogenetically informative, including vestibular reduction in Cetacea, a tall cochlear spiral in caviomorph rodents, a low position of the plane of the lateral semicircular canal compared to the posterior canal in Cetacea and Carnivora, and a low cochlear aspect ratio in Primatomorpha. SIGNIFICANCE The morphological descriptions that are presented add a broad baseline of anatomy of the inner ear across many placental mammal clades, for many of which the structure of the bony labyrinth is largely unknown. The data included here complement the growing body of literature on the physiological and phylogenetic significance of bony labyrinth structures in mammals, and they serve as a source of data for future studies on the evolution and function of the vertebrate ear.
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Affiliation(s)
- Eric G. Ekdale
- Department of Biology, San Diego State University, San Diego, California, United States of America
- Department of Paleontology, San Diego Natural History Museum, San Diego, California, United States of America
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The Bony Labyrinth in Diprotodontian Marsupial Mammals: Diversity in Extant and Extinct Forms and Relationships with Size and Phylogeny. J MAMM EVOL 2013. [DOI: 10.1007/s10914-013-9228-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Modern Imaging Techniques as a Window to Prehistoric Auditory Worlds. INSIGHTS FROM COMPARATIVE HEARING RESEARCH 2013. [DOI: 10.1007/2506_2013_32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Lautenschlager S, Rayfield EJ, Altangerel P, Zanno LE, Witmer LM. The endocranial anatomy of therizinosauria and its implications for sensory and cognitive function. PLoS One 2012; 7:e52289. [PMID: 23284972 PMCID: PMC3526574 DOI: 10.1371/journal.pone.0052289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 11/14/2012] [Indexed: 11/26/2022] Open
Abstract
Background Therizinosauria is one of the most enigmatic and peculiar clades among theropod dinosaurs, exhibiting an unusual suite of characters, such as lanceolate teeth, a rostral rhamphotheca, long manual claws, and a wide, opisthopubic pelvis. This specialized anatomy has been associated with a shift in dietary preferences and an adaptation to herbivory. Despite a large number of discoveries in recent years, the fossil record for Therizinosauria is still relatively poor, and cranial remains are particularly rare. Methodology/Principal Findings Based on computed tomographic (CT) scanning of the nearly complete and articulated skull of Erlikosaurus andrewsi, as well as partial braincases of two other therizinosaurian taxa, the endocranial anatomy is reconstructed and described. The wider phylogenetic range of the described specimens permits the evaluation of sensory and cognitive capabilities of Therizinosauria in an evolutionary context. The endocranial anatomy reveals a mosaic of plesiomorphic and derived characters in therizinosaurians. The anatomy of the olfactory apparatus and the endosseous labyrinth suggests that olfaction, hearing, and equilibrium were well-developed in therizinosaurians and might have affected or benefited from an enlarged telencephalon. Conclusion/Significance This study presents the first appraisal of the evolution of endocranial anatomy and sensory adaptations in Therizinosauria. Despite their phylogenetically basal position among maniraptoran dinosaurs, therizinosaurians had developed the neural pathways for a well developed sensory repertoire. In particular olfaction and hearing may have played an important role in foraging, predator evasion, and/or social complexity.
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Ryan TM, Silcox MT, Walker A, Mao X, Begun DR, Benefit BR, Gingerich PD, Köhler M, Kordos L, McCrossin ML, Moyà-Solà S, Sanders WJ, Seiffert ER, Simons E, Zalmout IS, Spoor F. Evolution of locomotion in Anthropoidea: the semicircular canal evidence. Proc Biol Sci 2012; 279:3467-75. [PMID: 22696520 DOI: 10.1098/rspb.2012.0939] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa for which good postcranial fossil material and appropriate modern analogues are available. We report the results of an analysis of semicircular canal size variation in 16 fossil anthropoid species dating from the Late Eocene to the Late Miocene, and use these data to reconstruct evolutionary changes in locomotor adaptations in anthropoid primates over the last 35 Ma. Phylogenetically informed regression analyses of semicircular canal size reveal three important aspects of anthropoid locomotor evolution: (i) the earliest anthropoid primates engaged in relatively slow locomotor behaviours, suggesting that this was the basal anthropoid pattern; (ii) platyrrhines from the Miocene of South America were relatively agile compared with earlier anthropoids; and (iii) while the last common ancestor of cercopithecoids and hominoids likely was relatively slow like earlier stem catarrhines, the results suggest that the basal crown catarrhine may have been a relatively agile animal. The latter scenario would indicate that hominoids of the later Miocene secondarily derived their relatively slow locomotor repertoires.
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Affiliation(s)
- Timothy M Ryan
- Department of Anthropology and Center for Quantitative Imaging, EMS Energy Institute, Pennsylvania State University, University Park, PA 16802, USA.
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Gunz P, Ramsier M, Kuhrig M, Hublin JJ, Spoor F. The mammalian bony labyrinth reconsidered, introducing a comprehensive geometric morphometric approach. J Anat 2012; 220:529-43. [PMID: 22404255 PMCID: PMC3390507 DOI: 10.1111/j.1469-7580.2012.01493.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2012] [Indexed: 11/29/2022] Open
Abstract
The bony labyrinth in the temporal bone houses the sensory systems of balance and hearing. While the overall structure of the semicircular canals and cochlea is similar across therian mammals, their detailed morphology varies even among closely related groups. As such, the shape of the labyrinth carries valuable functional and phylogenetic information. Here we introduce a new, semilandmark-based three-dimensional geometric morphometric approach to shape analysis of the labyrinth, as a major improvement upon previous metric studies based on linear measurements and angles. We first provide a detailed, step-by-step description of the measurement protocol. Subsequently, we test our approach using a geographically diverse sample of 50 recent modern humans and 30 chimpanzee specimens belonging to Pan troglodytes troglodytes and P. t. verus. Our measurement protocol can be applied to CT scans of different spatial resolutions because it primarily quantifies the midline skeleton of the bony labyrinth. Accurately locating the lumen centre of the semicircular canals and the cochlea is not affected by the partial volume and thresholding effects that can make the comparison of the outer border problematic. After virtually extracting the bony labyrinth from CT scans of the temporal bone, we computed its midline skeleton by thinning the encased volume. On the resulting medial axes of the semicircular canals and cochlea we placed a sequence of semilandmarks. After Procrustes superimposition, the shape coordinates were analysed using multivariate statistics. We found statistically significant shape differences between humans and chimpanzees which corroborate previous analyses of the labyrinth based on traditional measurements. As the geometric relationship among the semilandmark coordinates was preserved throughout the analysis, we were able to quantify and visualize even small-scale shape differences. Notably, our approach made it possible to detect and visualize subtle, yet statistically significant (P = 0.009), differences between two chimpanzee subspecies in the shape of their semicircular canals. The ability to discriminate labyrinth shape at the subspecies level demonstrates that the approach presented here has great potential in future taxonomic studies of fossil specimens.
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Affiliation(s)
- Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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The braincase of the basal sauropod dinosaur Spinophorosaurus and 3D reconstructions of the cranial endocast and inner ear. PLoS One 2012; 7:e30060. [PMID: 22272273 PMCID: PMC3260197 DOI: 10.1371/journal.pone.0030060] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 12/12/2011] [Indexed: 11/19/2022] Open
Abstract
Background Sauropod dinosaurs were the largest animals ever to walk on land, and, as a result, the evolution of their remarkable adaptations has been of great interest. The braincase is of particular interest because it houses the brain and inner ear. However, only a few studies of these structures in sauropods are available to date. Because of the phylogenetic position of Spinophorosaurus nigerensis as a basal eusauropod, the braincase has the potential to provide key evidence on the evolutionary transition relative to other dinosaurs. Methodology/Principal Findings The only known braincase of Spinophorosaurus (‘Argiles de l'Irhazer’, Irhazer Group; Agadez region, Niger) differs significantly from those of the Jurassic sauropods examined, except potentially for Atlasaurus imelakei (Tilougguit Formation, Morocco). The basisphenoids of Spinophorosaurus and Atlasaurus bear basipterygoid processes that are comparable in being directed strongly caudally. The Spinophorosaurus specimen was CT scanned, and 3D renderings of the cranial endocast and inner-ear system were generated. The endocast resembles that of most other sauropods in having well-marked pontine and cerebral flexures, a large and oblong pituitary fossa, and in having the brain structure obscured by the former existence of relatively thick meninges and dural venous sinuses. The labyrinth is characterized by long and proportionally slender semicircular canals. This condition recalls, in particular, that of the basal non-sauropod sauropodomorph Massospondylus and the basal titanosauriform Giraffatitan. Conclusions/Significance Spinophorosaurus has a moderately derived paleoneuroanatomical pattern. In contrast to what might be expected early within a lineage leading to plant-eating graviportal quadrupeds, Spinophorosaurus and other (but not all) sauropodomorphs show no reduction of the vestibular apparatus of the inner ear. This character-state is possibly a primitive retention in Spinophorosaurus, but due the scarcity of data it remains unclear whether it is also the case in the various later sauropods in which it is present or whether it has developed homoplastically in these taxa. Any interpretations remain tentative pending the more comprehensive quantitative analysis underway, but the size and morphology of the labyrinth of sauropodomorphs may be related to neck length and mobility, among other factors.
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Collin SP. The Neuroecology of Cartilaginous Fishes: Sensory Strategies for Survival. BRAIN, BEHAVIOR AND EVOLUTION 2012; 80:80-96. [DOI: 10.1159/000339870] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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The bony labyrinth of the early platyrrhine primate Chilecebus. J Hum Evol 2010; 59:595-607. [PMID: 20952046 DOI: 10.1016/j.jhevol.2010.06.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 03/31/2010] [Accepted: 06/25/2010] [Indexed: 11/24/2022]
Abstract
We document the morphology of the bony labyrinth of Chilecebus carrascoensis, one of the best preserved early platyrrhines known, based on high resolution CT scanning and 3D digital reconstruction. The cochlea is low and conical in form, as in other anthropoids, but has only 2.5 spiral turns. When the allometric relationship with body mass is considered, cochlear size is similar to that in extant primates. The relative size of the semicircular canals, which is well within the range of other primates, indicates that Chilecebus carrascoensis was probably not as agile in its locomotion as other small-bodied platyrrhines such as Leontopithecus rosalia, Saguinus oedipus, and Callithrix jacchus, but it probably was not a suspensory acrobat or a slow climber. The proportion, shape, and orientation of the semicircular canals in Chilecebus carrascoensis also mirror that typically seen in extant primates. However, no single variable can be used for predicting the locomotor pattern in Chilecebus carrascoensis. Based on Principle Component Analysis (PCA) scores we calculated rescaled Euclidean distances for various taxa; primates with similar locomotor patterns tend to share shorter distances. Results for Chilecebus carrascoensis underscore its general resemblance to living quadrupedal primate taxa, but it is not positioned especially near any single living taxon.
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Ekdale EG. Ontogenetic Variation in the Bony Labyrinth of Monodelphis domestica (Mammalia: Marsupialia) Following Ossification of the Inner Ear Cavities. Anat Rec (Hoboken) 2010; 293:1896-912. [DOI: 10.1002/ar.21234] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Straka H. Ontogenetic rules and constraints of vestibulo-ocular reflex development. Curr Opin Neurobiol 2010; 20:689-95. [PMID: 20637600 DOI: 10.1016/j.conb.2010.06.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 06/14/2010] [Accepted: 06/14/2010] [Indexed: 10/19/2022]
Abstract
Vestibulo-ocular reflexes (VOR) assist retinal image stabilization during vertebrate locomotion thereby ensuring accurate visual perception. The importance of this motor behavior for animal survival requires that the underlying circuitry and all individual components are fully developed and functional as soon as post-embryonic animals initiate self-motion. Recent progress on the genetic, molecular, and activity-dependent regulation of placode development, vestibular sensory organ formation, circuit assembly, and acquisition of neuronal properties revealed rules and restrictions that give insight into how hindbrain VOR neuronal networks are assembled and become functional during ontogeny. Major crucial steps that correlate with early/delayed functional VOR onsets concern the maturation of cellular properties (precocial/altricial species) and the acquisition of minimal semicircular canal dimensions (small-sized vertebrates).
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Affiliation(s)
- Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstr. 2, 82152 Planegg, Germany.
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Evangelista C, Mills M, Siebeck UE, Collin SP. A comparison of the external morphology of the membranous inner ear in elasmobranchs. J Morphol 2010; 271:483-95. [DOI: 10.1002/jmor.10812] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Witmer LM, Ridgely RC. New Insights Into the Brain, Braincase, and Ear Region of Tyrannosaurs (Dinosauria, Theropoda), with Implications for Sensory Organization and Behavior. Anat Rec (Hoboken) 2009; 292:1266-96. [DOI: 10.1002/ar.20983] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Dynamic displacement of normal and detached semicircular canal cupula. J Assoc Res Otolaryngol 2009; 10:497-509. [PMID: 19513793 PMCID: PMC2774407 DOI: 10.1007/s10162-009-0174-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 05/04/2009] [Indexed: 11/25/2022] Open
Abstract
The dynamic displacement of the semicircular canal cupula and modulation of afferent nerve discharge were measured simultaneously in response to physiological stimuli in vivo. The adaptation time constant(s) of normal cupulae in response to step stimuli averaged 36 s, corresponding to a mechanical lower corner frequency for sinusoidal stimuli of 0.0044 Hz. For stimuli equivalent to 40–200 deg/s of angular head velocity, the displacement gain of the central region of the cupula averaged 53 nm per deg/s. Afferents adapted more rapidly than the cupula, demonstrating the presence of a relaxation process that contributes significantly to the neural representation of angular head motions by the discharge patterns of canal afferent neurons. We also investigated changes in time constants of the cupula and afferents following detachment of the cupula at its apex—mechanical detachment that occurs in response to excessive transcupular endolymph pressure. Detached cupulae exhibited sharply reduced adaptation time constants (300 ms–3 s, n = 3) and can be explained by endolymph flowing rapidly over the apex of the cupula. Partially detached cupulae reattached and normal afferent discharge patterns were recovered 5–7 h following detachment. This regeneration process may have relevance to the recovery of semicircular canal function following head trauma.
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