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In the dog these small bones are called tympanohyal (upper) and stylohyal (lower). In evolutionary terms, the temporal bone is derived from the fusion of many bones that are often separate in non-human mammals: The squamosal bone, which is homologous with the squama, and forms the side of the cranium in many bony fish and tetrapods.
These extended margins of thinned bone are called supratemporal fossae. Synapsids, including mammals, have one temporal fenestra, which is ventrally bordered by a zygomatic arch composed of the jugal and squamosal bones. This single temporal fenestra is homologous to the infratemporal fenestra, as displayed most clearly by early synapsids. [2]
The full complement of bones of the tetrapod skull roof, as seen in the temnospondyl Xenotosuchus. The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium.
1 occipital bone; 2 parietal bones; 1 sphenoid bone; 2 temporal bones; The ossicles (three on each side) are usually not included as bones of the neurocranium. [6] There may variably also be extra sutural bones present. Below the neurocranium is a complex of openings and bones, including the foramen magnum which houses
The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally, the lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian ...
The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines above, and the zygomatic arch below. Its floor is formed by the outer surfaces of four bones of the skull. The fossa is filled by the temporalis muscle.
A craniate is a member of the Craniata (sometimes called the Craniota), a proposed clade of chordate animals with a skull of hard bone or cartilage.Living representatives are the Myxini (hagfishes), Hyperoartia (including lampreys), and the much more numerous Gnathostomata (jawed vertebrates).
Several of these bones merge, and in the adult primates (including humans), the endocranium is composed of only five bony elements (from front to back): [4] The ethmoid bone, lying behind the nose. The sphenoid bone, underlying the forward portion of the brain; Paired petrous part of the temporal bones, containing the inner ear structures