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THE SKULL OF REPTILES
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Fig. 66. Phytosaur skull: Machaeroprosopus, from above and from below.
either cylindrical throughout or partly or chiefly flattened and denticulated. The first two or three teeth on each side, especially above, are cylindrical and much elongated. The dentulous portion of the premaxillae is long, with twenty or more teeth on each side.
The chief differences in the skull structure of the various members of the order are found in the relative position of the external nares,
