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Giganotosaurus did not have a sagittal crest on the top of the skull, and the jaw muscles did not extend onto the skull roof, unlike in most other theropods (due to the shelf over the supratemporal fenestrae). These muscles would instead have been attached to the lower side surfaces of the shelf.
The four classical muscles of mastication elevate the mandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the geniohyoid , mylohyoid , and digastric muscles (the lateral pterygoid may play a role).
The tips of their upper and lower jaws fanned out into a spoon-shaped structure similar to a rosette, behind which there was a notch in the upper jaw that the expanded tip of the lower jaw fit into. The nostrils of spinosaurids were retracted to a position further back on the head than in most other theropods, and they had bony crests on their ...
The mandible consists of both endochondral bones, which ossified from the Meckelian cartilage, and dermal bones. [5] In dinosaurs, only the dentary bears teeth. [25]: 40 mandibular fenestra The external mandibular fenestra is an opening in the lower jaw between the dentary, surangular, and angular bones. It is characteristic for archosauriforms ...
The zygomasseteric system (or zygomasseteric structure) in rodents is the anatomical arrangement of the masseter muscle of the jaw and the zygomatic arch of the skull. The anteroposterior or propalinal (front-to-back) motion of the rodent jaw is enabled by an extension of the zygomatic arch and the division of the masseter into a superficial, lateral and medial muscle.
The dentary (tooth-bearing lower jaw bone) was squared off at the front edge, as in Giganotosaurus, and shallow, while the rest of the jaw behind it became very deep. Acrocanthosaurus and Giganotosaurus shared a thick horizontal ridge on the outside surface of the surangular bone of the lower jaw, underneath the articulation with the skull. [7]
This is an accepted version of this page This is the latest accepted revision, reviewed on 30 January 2025. Extinct family of dinosaurs Carcharodontosaurids Temporal range: 154–90 Ma Pre๊ ๊ O S D C P T J K Pg N Reconstructed Carcharodontosaurus skull, Science Museum of Minnesota Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Chordata Clade: Dinosauria Clade ...
The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. The sagittal crest serves primarily for attachment of the temporalis muscle, which is one of the main chewing muscles. Development of the sagittal crest is thought to be connected to the development of this muscle.