THE SKULL OF REPTILES 



67 



The squamosal normally articulates with the tabular and quad- 

 rate posteriorly, anteriorly with the postorbital, and often, both in 

 the lizards and mosasaurs, by a slender prolongation with the tip of 



Fig. 54. Mosasaur skulls: Upper figure, Clidastes, from the side; middle figure, 

 Platecarpus, from below; lower figure, Tylosatirus, from above, an, angular; 

 bs, basisphenoid; c, coronoid; ep, epipterygoid; /r, frontal; j, jugal; /, lacri- 

 mal; m, maxilla; na, nasal; oc, occipital condyle; pa, parietal, palatine; pm, 

 premaxilla; pj, prefrontal; pt, pterygoid; po, postorbital; q, quadrate; sp, 

 splenial; sq, squamosal; tr, transverse; v, vomer. 



the jugal; very rarely, as in Uromastix, with the jugal only. In 

 some lizards it has suffered reduction, and is absent in the Geck- 

 onidae, Anniella, and Amphisbaenidae, vestigial in the Heloder- 

 matidae. 



