120 



82) inflation of medial portion of caudal entotympanic: 0 = not inflated; 1 = slight / 

 moderate inflation; 2 = inflated (Wozencraft 1989) (Fig. 22). 



According to Wozencraft (1989), the inflation of the medial portion of the entotympanic 

 possesses the same distribution as the previous character: canids, procyonids, mustelids 

 (excluding lutrines and mephitines), and phocids. However, in this case, our observations 

 disagree slightly with those of Wozencraft (1989). Again, the polarity is reversed for the 

 caniforms, with the inflated morphology being primitive. As well, this condition is largely 

 retained throughout the caniforms, with only Ursus (state 1), the otarioids (state 0), and 

 the monachines Hydrurga, Monachus spp., and Ommatophoca (states 0 or 1, or both) 

 showing a reduction in the inflation of this portion of the entotympanic. 



83) distinct sulcus dividing ectotympanic and entotympanic portions of auditory bulla: 0 

 = absent; 1 = present (Burns & Fay 1970) (Fig. 22). 



In discussing the auditory bulla of Histriophoca, Burns & Fay (1970) noted the presence 

 of a distinct sulcus dividing the ectotympanic and entotympanic regions in a number of 

 specimens. This sulcus is also very distinct in Cystophora, and is apparently present, 

 although less distinct, in other phocids as well (van der Klaauw 1931). Although we 

 observed this sulcus to varying degrees in many phocids (primarily the monachines), these 

 seem to be the sole descriptions of this feature, except for a quick note by Howell (1928) 

 concerning the virtual obliteration of the suture in a fetal Phoca vitulina. However, the 

 apomorphic expression of a distinct sulcus is uncommon, being found only in Martes and 

 the clade of Monachus schauinslandi and Monachus tropicalis. Although numerous 

 isolated pinniped specimens possessed rudimentary sulci (coded here as a polymorphism), 

 this morphology was only manifested at the species level for Odobenus, Hydrurga, and 

 Leptonychotes. 



84) relationship between auditory bulla and petrosal: 0 = does not cover petrosal; 1 = 

 covers petrosal (King 1966; Wyss 1988a). 



King (1966) initially noted the condition whereby the petrosal projects into the posterior 

 lacerate foramen of phocines and Monachus spp. (also de Muizon 1982a). As this condition 

 also obtains in Odobenus and certain fossil pinnipeds, Wyss (1988a) regarded this 

 morphology as likely being primitive at some level higher than the phocids. As exposure 

 of the petrosal is a mechanism to improve hearing underwater (Repenning 1972; de 

 Muizon 1982a), this condition is, at best, primitive at the level of the lutrines, but more 

 likely the pinnipeds as a whole. De Muizon & Hendey (1980) regarded the converse state 

 (state 1) as diagnostic of the lobodontines. However, Ray (1976b) urged caution in 

 employing both this character and related ones, as the complexity of the general region 

 does not lend itself to being reduced to simple characters. As well, the polymorphic nature 

 of Leptonychotes and Ommatophoca for this character, and the difficulties in distinguishing 

 between the petrosal and mastoid in this region create additional problems (Ray 1976b). 

 Our analysis indicates an opposite polarity for this character to that of Wyss (1988a). Here, 

 state 1 is primitive among the Caniformia and the derived condition is found convergently 

 between the lutrines, all phocines, and Monachus spp. The occurrence of the derived 

 condition in both Enhydra and Lutra may represent either convergent evolution 



