. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CRANIAL MORPHOLOGY OF PRISTERODON BUFFALOENSIS H3 influence in swinging the snout sideways. The major would also pull the skull back but the forward slant of the hind wall of the skull dorsal to the fora- men magnum suggests that its contraction would also lever the snout upwards. This action would allow the animal to tear off portions from its food source which are small enough to be handled by the jaws. The ventral half of the distal portion of the opisthotic served as origin for the obliquu
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CRANIAL MORPHOLOGY OF PRISTERODON BUFFALOENSIS H3 influence in swinging the snout sideways. The major would also pull the skull back but the forward slant of the hind wall of the skull dorsal to the fora- men magnum suggests that its contraction would also lever the snout upwards. This action would allow the animal to tear off portions from its food source which are small enough to be handled by the jaws. The ventral half of the distal portion of the opisthotic served as origin for the obliquus capitis. Contraction of this muscle which in living reptiles is inserted on the neural arch of the axis and atlas, would cause a lateral swing of the skull. Between this muscle and the lateral portion of the one above it ( lateralis et medialis) the opisthotic is drawn out into a pointed posteriorly projecting process, which may be called the opisthotic process for lack of a more suitable name. Stresses caused by the contraction of these two functionally important but differently directed muscles would seem to be the main reason for the develop- ment of the opisthotic process. Cox (1959) contends that this process, which he called the 'tympanic process', was not concerned with the occipital musculature. Comparison of Pristerodon with living chelonians gives strong indications that the two muscle groups mentioned not only flanked the process dorso-medially and ventro-medially respectively, but were also attached along part of the process. It is of interest to note that some of the recent turtles show an analagous. Fig. 8. Pristerodon buffaloensis. Sectioned specimen. Reconstructions of A: medial view of posterior third of the skull; B: lateral view of impression of left membranous labyrinth; C: medial view of stapes footplate; D: dorsal view of right stapes; E: lateral view of quadrate face of the right stapes; F: ventral view of right stapes; G: posterior view of right
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
