Figure 76.— Batistes polylepis: ventral 



(left) and dorsal (right) views of skull, 



ca. 390 mm SL, Mexico. 



Relationship to the Triacanthidae.— The presence 

 in balistids of such features as a well-developed spiny 

 dorsal fin, a well-developed pelvis with a pelvic fin 

 (even though highly modified), discrete teeth in the jaws, 

 a caudal fin with 12 rays, supported by a complex 

 with a free epural and parhypural, and a free palatine 

 obviously relates the balistids to the triacanthoids, 

 while a number of characteristics shared by balistids 

 and triacanthids but not by triacanthodids indicates 

 that the triacanthids are the most closely related ances- 

 tral group of the balistids. 



The main features of similarity between balistids and 

 triacanthids, followed by the dissimilar condition in 

 triacanthodids, as mostly summarized from Tyler (1968), 

 are: 1) large heavy incisorlike teeth in an outer series 

 and more molariform teeth in the inner series versus 

 relatively smaller, conical to wide and thin in an outer 

 series £md, when present, of the same type in an inner 

 series; 2) hyomandibular with a well-developed crest 

 across its outer surface versus no such crest; 3) pterotic 

 with a large ventral flange over the posterodorsal end of 

 the hyomandibular versus no such flange; 4) operculum 



