42 
The surangular anteriorly overlaps the thin lower posterior termination 
of the dentary, the excavation of the anterior portion of its upper surface 
forming the hinder part of the floor of the mandibular fossa. Its slender 
antero-exterior prolongation or limb fits closely against and runs high 
up on the inner side of the posterior border of the coronoid process. An 
impressed area of triangular outline, narrowing backward, on the lower 
Figure 22. Right surangular of Edmontosaurus, Cat. No. 2289; j natural size. 
A, external aspect; B, internal aspect; C, superior aspect; an, surface for angu- 
lar; ar, surface for articular; cot, cotylus for distal end of quadrate; cp, surface 
for coronoid process; dn, for dentarjq mf, mandibular fossa. 
surface of the bone in its anterior half, and continuing upward as a decided 
flattening of the limb on its outer side, marks the full extent of the contact 
of the surangular with the dentary. The inner backward extension is 
closely applied from beneath to the articular which, in its more posterior 
part, is between this extension of the surangular and the splenial, and 
