title: Bony labyrinth morphometry indicates locomotor adaptations in the squirrel-related clade (Rodentia, Mammalia).
abstract: The semicircular canals (SCs) of the inner ear detect angular acceleration and are located in the bony labyrinth of the petrosal bone. Based on high-resolution computed tomography, we created a size-independent database of the bony labyrinth of 50 mammalian species especially rodents of the squirrel-related clade comprising taxa with fossorial, arboreal and gliding adaptations. Our sampling also includes gliding marsupials, actively flying bats, the arboreal tree shrew and subterranean species. The morphometric anatomy of the SCs was correlated to the locomotion mode. Even if the phylogenetic signal cannot entirely be excluded, the main significance for functional morphological studies has been found in the diameter of the SCs, whereas the radius of curvature is of minor interest. Additionally, we found clear differences in the bias angle of the canals between subterranean and gliding taxa, but also between sciurids and glirids. The sensitivity of the inner ear correlates with the locomotion mode, with a higher sensitivity of the SCs in fossorial species than in flying taxa. We conclude that the inner ear of flying and gliding mammals is less sensitive due to the large information flow into this sense organ during locomotion.
authors.affiliation: Department of Palaeontology, Geozentrum, University of Vienna, Althanstrasse 14, Vienna 1090, Austria cathrin.pfaff@univie.ac.at.
authors.forename: Cathrin
authors.initials: C
authors.lastname: Pfaff
authors.affiliation: Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, Bonn 53115, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Martin
authors.affiliation: Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Abteilung Paläoanthropologie und Messelforschung, Senckenberganlage 25, Frankfurt am Main 60325, Germany.
authors.forename: Irina
authors.initials: I
authors.lastname: Ruf
mesh_terms: D000818:Animals; D002685:Chiroptera / Q000033:anatomy & histology / Q000502:physiology; D008124:Locomotion; D008322:Mammals / Q000033:anatomy & histology / Q000502:physiology; D012377:Rodentia / Q000033:anatomy & histology* / Q000502:physiology*; D012589:Sciuridae / Q000033:anatomy & histology; D012665:Semicircular Canals / Q000000981:diagnostic imaging*; D055114:X-Ray Microtomography / Q000662:veterinary
keywords: Rodentia; inner ear; locomotion; morphometry; semicircular canals; vestibular system