title: Bite force in the extant coelacanth Latimeria: the role of the intracranial joint and the basicranial muscle.
abstract: The terrestrialization process involved dramatic changes in the cranial anatomy of vertebrates. The braincase, which was initially divided into two portions by the intracranial joint in sarcopterygian fishes, became consolidated into a single unit in tetrapods and lungfishes [1-3]. The coelacanth Latimeria is the only extant vertebrate that retains an intracranial joint, which is associated with a unique paired muscle: the basicranial muscle. The intracranial joint has long been thought to be involved in suction feeding by allowing an extensive elevation of the anterior portion of the skull, followed by its rapid depression driven by the basicranial muscle [4-7]. However, we recently challenged this hypothesis [8, 9], and the role of the basicranial muscle with respect to the intracranial joint thus remains unclear. Using 3D biomechanical modeling, we show here that the basicranial muscle and the intracranial joint are involved in biting force generation. By flexing the anterior portion of the skull at the level of the intracranial joint, the basicranial muscle increases the overall bite force. This likely allows Latimeria to feed on a broad range of preys [10, 11] and coelacanths to colonize a wide range of environments during their evolution [4]. The variation in the morphology of the intracranial joint observed in Devonian lobe-finned fishes would have impacted to various degrees their biting performance and might have permitted feeding specializations despite the stability in their lower jaw morphology [12]. VIDEO ABSTRACT.
authors.affiliation: RIKEN Evolutionary Morphology Laboratory, Kobe Hyogo 650-0047, Japan. Electronic address: hugo.dutel@riken.jp.
authors.forename: Hugo
authors.initials: H
authors.lastname: Dutel
authors.affiliation: UMR 7179 CNRS-MNHN, Mécanismes Adaptatifs: des Organismes aux Communautés, Département Écologie et Gestion de la Biodiversité, Muséum National d'Histoire Naturelle, 75231 Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Herbin
authors.affiliation: Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P, UMR 7207), Sorbonne Universités, MNHN, CNRS, UPMC-Paris 6, Muséum National d'Histoire Naturelle, 57 rue Cuvier, CP38, 75005 Paris, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Clément
authors.affiliation: UMR 7179 CNRS-MNHN, Mécanismes Adaptatifs: des Organismes aux Communautés, Département Écologie et Gestion de la Biodiversité, Muséum National d'Histoire Naturelle, 75231 Paris, France; Evolutionary Morphology of Vertebrates, Ghent University, K.L. Ledeganckstraat 35, 9000 Gent, Belgium.
authors.forename: Anthony
authors.initials: A
authors.lastname: Herrel
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001732:Bite Force; D005399:Fishes / Q000502:physiology*; D007568:Jaw / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology