132 



and pointed. In Monachus spp., the petrosal apex is intermediate between these two 

 extremes (de Muizon 1982a; Wyss 1988a). Wyss (1988a) only employed the two extreme 

 states (homologizing the condition in Monachus spp. with the non-phocid condition); 

 however, there is cause to recognize the intermediate state. Only the phocines and 

 Mirounga spp. are accurately described as possessing a globular apex. In the lobodontines, 

 the enlarged apex is more of a lower and broader structure (Hendey & Repenning 1972; 

 Ray 1976b). 



The distinction between the phocid subfamilies seems to be minimal, however. Despite 

 claims by Repenning (1975), Odobenus was not held to possess an expanded apex (but 

 was noted to have an expanded dorsal petrosal region in general; see previous character), 

 and an expanded apex was synapomorphic for the phocids only and generally retained 

 throughout the family. Only Lobodon (state 1) and Monachus spp. (state 0) showed 

 predispositions towards returning to a plesiomorphic, unexpanded petrosal apex. 



115) roof of internal auditory meatus: 0 = reduced; 1 = full internal auditory meatus (Wyss 

 1988a). 



The phocids are distinguished from the remaining pinnipeds (and most other mammals) 

 by the complete reduction of the internal auditory meatus, resulting in separate entrances 

 for the facial and auditory nerves (Gray 1905; Wyss 1988a). Wyss (1988a) further noted 

 that in conjunction with this reduction, the petrosal lip forming the roof of the internal 

 auditory meatus is absent, or, in the case of Monachus spp., reduced to a bony spur. We 

 have chosen to separate these two features dealing with the status of the internal auditory 

 meatus and the condition of its former roof (see the following character), as they apparently 

 diagnose synapomorphies of different sets of taxa. For this character, the reduction of the 

 internal auditory meatus is indeed a synapomoiphy uniting all phocids. 



116) bony spur of roof of internal auditory meatus: 0 = absent; 1 = present (Wyss 1988a). 

 As indicated under the previous character, the reduction of the internal auditory meatus 

 in phocids typically results in the complete loss of the petrosal lip forming its roof. 

 However, in Monachus spp., a bony spur remains and projects medially above the canals 

 of the facial and auditory nerves (Wyss 1988a). Given the typical basal placement of this 

 genus in the phocids, Wyss (1988a) has implicated this morphology as an intermediate 

 stage leading to the complete loss of the petrosal roof. Instead, the possession of a bony 

 spur (or more properly, the incomplete reduction of the petrosal roof) appears to be a 

 synapomorphy linking Monachus schauinslandi and Monachus tropicalis, although we 

 also noted it in isolated specimens of Halichoerus, Leptonychotes, Mirounga leonina, 

 Monachus monachus, Pusa caspica, and Pusa hispida. The plesiomorphic condition, where 

 the spur is absent, is really a combination of two distinct morphologies. In the remaining 

 phocids, the spur is truly absent and the petrosal lip is typically quite broad, but with 

 virtually no medial expansion. In some taxa (e.g., Mirounga leonina), even the lip is 

 lacking entirely. Meanwhile, in non-phocids, the spur is "present", but not visible, as it is 

 subsumed within the complete petrosal roof of the internal auditory meatus. 



117) inflation of bullar chamber: 0 = not inflated; 1 = inflated (Wozencraft 1989). 



As implied by Repenning (1972), this character provides a truer measure of the inflation 

 of the auditory bulla (see characters #80-82). However, as we were limited in most cases 



