103 



vacuity of phocines is generally separate from the maxillo-frontal suture, in contrast to 

 the observations of Burns & Fay (1970). This state also defines the ancestral phocid 

 condition. Correspondingly, the more expanded vacuity of monachines is generally 

 confluent with the maxillo-frontal suture, especially in the clade composed of Lobodon, 

 Monachus spp., and Ommatophoca. This condition also arises convergently in Zalophus. 



44) relative vertical position of optic foramina: 0 = in lower third of interorbital region; 

 1 = between lower third and upper two-thirds of interorbital region; 2 - in upper two- 

 thirds of interorbital region (pers. obs.) (Fig. 20). 



Observations for other characters related to the optic foramina (characters #45-47) revealed 

 that the foramina are not at a constant relative height in the skull. The most common 

 condition was for the foramina to be situated about one-third of the way up the interorbital 

 region (state 1), with displacements to varying degrees occurring both above (state 2) and 

 below (state 0) this apparent demarcation point. 



In fact, a ventral displacement of the optic foramina (state 0) is primitive among caniforms, 

 being found in all fissipeds except Lutra. Lutra instead groups with the pinnipeds in 

 possessing state 1. Three major groups roughly fall out within the pinnipeds. The otarioids 

 are clearly defined by dorsally displaced foramina (state 2), while the phocines (excepting 

 Cystophora and Halichoerus) revert to the primitive condition. The monachines generally 

 retain the ancestral pinniped morphology (state 1). although Hydrurga and Mirounga 

 leonina independently obtain the otarioid condition. 



45) intracranial openings of optic foramina of orbitosphenoid: 0 = separate; 1 = converging 

 / intermediate; 2 = confluent (Mivart 1885) (Fig.21). 



Mivart (1885) initially used a simpler form of this character to distinguish the otarioids 

 (state 2) from the phocids (state 0). Only Hydrurga, and possibly Lobodon, were noted to 

 deviate from this pattern (Mivart 1885). However, our observations revealed an apparent 

 intermediate condition (state 1) in addition to these two more extreme morphologies. This 

 intermediate state closely resembles state 2, except that each opening is still individually 

 distinguishable despite being reasonably confluent with the other. 



Within the Caniformia, any tendency towards confluence of the intracranial openings of 

 the optic foramina is apomorphic. Parallel appearances of the totally confluent morphology 

 (state 2) occur in the otarioids and generally in the monachines internal to Mirounga spp. 

 The apparent intermediate condition does not intervene between the two extreme 

 morphologies, but instead occurs independently several times within the Caniformia. 



46) interorbital septum anterior to optic foramina: 0 = absent: 1 = present (Wozencraft 

 1989) (Fig.20). 



To some degree, the interorbital septum reflects the narrowness of the interorbital region. 

 This septum is present in those taxa in which the optic foramina possess a common rostral 

 border (Wozencraft 1989), and is formed by the adpression and fusion of the paired wings 

 of the orbitosphenoid anterior to the optic foramina. The septum is typically identified 

 only with the otariids (Turner 1848; Wozencraft 1989). However, the phocids might also 

 be expected to possess an interorbital septum as the pinnipeds as a whole possess a 

 narrower interorbital region than do other carnivores (Howell 1928; see also character 



