The Bony Labyrinth in Diprotodontian Marsupial Mammals: Diversity in Extant and Extinct Forms and Relationships with Size and Phylogeny

Alloing-Séguier, Léanie; Sánchez‐Villagra, Marcelo R.; Lee, Michael S. Y.; Lebrun, Renaud

doi:10.1007/s10914-013-9228-3

Cited by 25 publications

(26 citation statements)

References 38 publications

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“…Focusing on the phylogenetic signal of the vestibular system, our study is in accordance to the assumption that ASC bears the highest phylogenetic signal of all three semicircular canals (Alloing‐Séguier et al, ). However, the phylogenetic signal of all morphological traits of the vestibular system is not that important as it was previously postulated (Alloing‐Séguier et al, ).…”

Section: Discussionsupporting

confidence: 86%

“…Anatomical investigations of the ear region in marsupials have either focused on the ontogeny of the middle ear ossicles (malleus, incus, stapes) (Alloing-S eguier, S anchez-Villagra, Le, & Lebrun, 2013;Doran, 1879;Fleischer, 1978;Gray, 1907;Hyrtl, 1873;Maier, 1989;Nummela & S anchez-Villagra, 2006;S anchez-Villagra, Gemballa, Nummela, Smith, & Maier, 2003;S anchez-Villagra & Nummela, 2001;Schmelzle, Nummela, & S anchez-Villagra, 2005), or on the vestibular system of diprotodontains with its diversity (Schmelzle, S anchez-Villagra, & Maier, 2007) and respective phylogenetic value (Alloing-S eguier et al, 2013) in the light of evolutionary and anatomical changes.…”

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confidence: 99%

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Functional morphological adaptations of the bony labyrinth in marsupials (Mammalia, Theria)

Pfaff

Czerny

Nagel

et al. 2017

Journal of Morphology

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Diprotodontia represents the largest and ecologically most distinct order of marsupials occurring in Australasian being highly divers in size, locomotion, habitat preferences, feeding, and activity pattern. The spatial orientation in the habitat and therefore the three-dimensional space is detected by the vestibular system of the inner ear, more precisely by the three semicircular canals. In this study, we investigated the bony labyrinth of diprotodontian and selected non-diprotodontian marsupial mammals of almost all genera with noninvasive micro-CT scanning and 3D-reconstructions. In principal component analyses, the subterranean taxon can be separated from gliding and saltatorial taxa, whereas arboreal species can be separated from saltatorial specimens. The highest PCA loadings of this functional distinction are clearly found in the diameter of the semicircular canals, whereas the overall shape (height, width, length) of the semicircular canals is less important. Additionally, the investigated arboreal and fossorial species of South America are nested in the morphospace of the Australasian taxa. Even if a phylogenetic signal in the anatomy of the bony labyrinth cannot be excluded entirely, the main functional morphological signal of the vestibular system is found in the diameter of the semicircular canals. With the large dataset of extant marsupial mammals analysed here, the locomotion mode of extinct taxa can be inferred in future studies independent of any evidence of postcranial material.

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Section: Discussionsupporting

confidence: 86%

mentioning

confidence: 99%

Functional morphological adaptations of the bony labyrinth in marsupials (Mammalia, Theria)

Pfaff

Czerny

Nagel

et al. 2017

Journal of Morphology

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“…However, the allometric effects detected by Alloing‐Séguier et al. () and Lebrun et al. () in diprotodontian marsupials and primates on the relative sizes of the ASC, PSC, and LSC are not present in our xenarthran sample.…”

Section: Discussioncontrasting

confidence: 73%

The inner ear ofMegatheriumand the evolution of the vestibular system in sloths

et al. 2013

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Extant tree sloths are uniquely slow mammals with a very specialized suspensory behavior. To improve our understanding of their peculiar evolution, we investigated the inner ear morphology of one of the largest and most popular fossil ground sloths, Megatherium americanum. We first address the predicted agility of this animal from the scaling of its semicircular canals (SC) relative to body mass, based on recent work that provided evidence that the size of the SC in mammals correlates with body mass and levels of agility. Our analyses predict intermediate levels of agility for Megatherium, contrasting with the extreme slowness of extant sloths. Secondly, we focus on the morphology of the SC at the inner ear scale and investigate the shape and proportions of these structures in Megatherium and in a large diversity of extant xenarthrans represented in our database. Our morphometric analyses demonstrate that the giant ground sloth clearly departs from the SC morphology of both extant sloth genera (Choloepus, Bradypus) and is in some aspects closer to that of armadillos and anteaters. Given the close phylogenetic relationships of Megatherium with the extant genus Choloepus, these results are evidence of substantial homoplasy of the SC anatomy in sloths. This homoplasy most likely corresponds to an outstanding convergent evolution between extant suspensory sloth genera.

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“…; Alloing‐Séguier et al. ), and with the presence of proportionally larger labyrinths in more agile primates and other mammals (Spoor et al. ). The first principal component axis (PC1) correlates strongly, and negatively, to body mass (Table ).…”

Section: Discussionmentioning

confidence: 99%

“…; Alloing‐Séguier et al. ; other groups have not yet been studied). This proportional difference may relate to the greater potential for manoeuvrability in smaller‐bodied birds and mammals.…”

Section: Discussionmentioning

confidence: 99%

Comparative analysis of vestibular ecomorphology in birds

Benson

Starmer-Jones

et al. 2017

Journal of Anatomy

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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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The Bony Labyrinth in Diprotodontian Marsupial Mammals: Diversity in Extant and Extinct Forms and Relationships with Size and Phylogeny

Cited by 25 publications

References 38 publications

Functional morphological adaptations of the bony labyrinth in marsupials (Mammalia, Theria)

Functional morphological adaptations of the bony labyrinth in marsupials (Mammalia, Theria)

The inner ear ofMegatheriumand the evolution of the vestibular system in sloths

Comparative analysis of vestibular ecomorphology in birds

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