Answer
The kinetic skull is a kind of skull found in reptiles ( and some other animals ) that is capable of other movements between its parts besides the movement at the temporomandibular joint between upper and lower jawbones(.normal in mammals). The degree of cranial kinesis varies between animals with kinetic skulls. Birds, lizards , snakes all have kinetic skulls, so do did the therodant dinosaurs.
Cranial kinesis enables animals with the associated adaptations to open their mouths to produce a greater aperture than would be possible with just the temporomandibular jointed skull,
The advantage is that such animals are able to swallow larger objects or prey animals than would possible for mammals.
This is advantageous it because enables them to snatch the prey, secure it from competitors, and quickly move out of a danger zone where competitors may attempt to participate in the feast.
Work Step by Step
The hinge that joins the upper and lower jaws of mammals is the temporo-madibular joint. But many reptiles, and some dinosaurs have/had other joints between cranial (skull) bones:
Some dinosaurs had a joint between the frontal and parietal bones in the roof of the skull
All groups of the Lepidosauria-- lizards, snakes, Tuatara-- have kinetic skulls capable of different degrees of mobility
The Tuatara Rhynchophalia) of New Zealand have a joint in the floor of the skull between the basisphenoid and the pterygoid bones.
In lizards, greater movement was possible between the quadrate bone and the lower jaw because of changes in the temporal bone.
Snakes show the greatest degree of cranial kinesis; they possess upper jaws capable of of rotatory, as well as backward and forward
movements. In addition, some snakes have a snout that can move up and down because of a hinge between the roof of the skull and the naso-
frontal bone.
Contrary to popular folk belief , snakes cannot unhinge their lower jaws, but the kinetic skull confers amazing ability to swallow large prey.
whole.
