=== Non-mammalian
synapsids === In non-mammalian
synapsids, the jaw is composed of four bony elements and referred to as a quadro-articular jaw because the joint is between the
articular and
quadrate bones. In
therapsids (advanced synapsids including mammalians), the jaw is simplified into an articulation between the
dentary and the
squamous part of the
temporal bone, and hence referred to as a dentary-squamosal jaw.
Mammals In many mammals, including humans, the squamosal fuses with the
periotic bone and the
auditory bulla to form the
temporal bone, then referred to as the
squama temporalis. In mammals, the
quadrate bone evolves to form the
incus, one of the
ossicles of the mammalian ear. Similarly, the
articular bone evolves to form the
malleus. The squamosal bone migrates and lengthens to become a new point of articulation with the lower jaw (at the
dentary bone). == References ==