Related Experiment Video
Updated: May 13, 2026
Ocular Kinematics Measured by In Vitro Stimulation of the Cranial Nerves in the Turtle
Published on: June 2, 2018
The tendinous framework in the temporal skull region of turtles and considerations about its morphological
1Geowissenschaftliches Institut der Eberhard-Karls-Universität, Hölderlinstraβe 12, 72074 Tübingen / Germany. i.werneburg@gmail.com
Abstract:
In 1926, Tage Lakjer hypothesized a replacement of the infratemporal bar in diapsids by a ligament spanning between quadrate and the upper jaw. As a similar ligament is also present in turtles, he argued for a diapsid origin of this group. Based on recent advances in the homologization of the tendinous framework in the reptile jaw adductor chamber - reviewed in this paper - one could argue for independent origins of the cheek ligaments in sauropsids. The quadratomaxillar ligament of turtles could, with reservation, be homologized with the quadrate aponeurosis of other sauropsids, as well as to the superficial tendon of m. masseter in mammals. These structures have a strong morphogenetic influence to cranial anatomy. Given such an identity, the hypothesis of a structural replacement of the lower temporal arcade in lizards would be refuted. Moreover, such a homology could be correlated to the evolution of the middle ear and to the origin of the chewing mechanism in mammals, which contributed to the evolutionary success of that group. The homologization presented herein is critically discussed and is open for revision. Nevertheless, the value of tendinous structures for fundamental homologisations in the vertebrate head is highlighted.
Related Concept Videos
01:22Sutures of the Skull
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...
01:27Cranial Bones: Lateral View
The temporal bone forms the lower lateral side of the skull. The temporal bone is subdivided into several regions. The flattened upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting...
01:08Overview of the Skull
The cranial vault surrounds and protects the brain and houses the middle and inner ear structures. This cavity is bounded superiorly by the rounded top of the skull, which...
01:14Cranial Bones: Superior and Posterior View
The frontal bone is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella. The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin,...
01:29Bone Formation by Intramembranous Ossification
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into...
01:09Overview of the Axial Skeleton
The axial skeleton of the adult...