orbital cartilage 

 interorbital septum 



frontal 



olfactory fenestra 

 prefrontal 

 lacrimal 

 nasal 



dentary 



epioptic fenestra 

 ptic fenestra 

 trochlear foramen (IV) 

 postorbital 



splenial 



ascencJing process 



squamosal 

 columella 

 perilymphatic fenestra 



quadrate 



angular 



suproongulor 



anterior cupola. 



nasal septum 



optic fenestra 



epioptic fenestra 

 taenia marginalts. 



metoptic fenestra j£i 



premaxilla 

 nasal 



prefrontal 



premaxilla. 



prefronta 



prenasal process 



foramen apicole 



parosphenoid 



prootic fenestra 



pterygoid 

 process 



ascending process 



—postorbital. 



basipterygoid process 



cranioquadrote fissure 

 pterygoid process 



squamosal 



_ jugular \ 



endolymphatic foramen t"--'^ , _i 



foramen magnum notocriord canal 



Figure 4-12. Chondrocranium and some of the dermal bone rudiments observed in the head of an 

 embryo (13-mm head length) of CrococJ/7us biporcofus. (After Shiino, 1914) 



Bird 



The head skeleton of the chicken, as an example of the 

 bird, contributes several useful points to the discussion of the 



nature and evolution of the osseous system. The type of flight 

 practiced by the bird demands a high level of development 

 of the eye and brain for the coordination and direction of 

 action. Both of these features are reflected in the head in 



OTHER TETRAPODS • 75 



