148 



A mandibular flange (or an elongated symphysis) was noted by King (1972, 1983) for 

 Odobenus, Erignathus, Lobodon, Pagophilus, Phoca spp., and Pusa spp., where the 

 resultant scoop-like mandible was postulated to be an adaptation for a "sucking" mode of 

 feeding [best described for Odobenus; see Fay (1982)]. This flange may represent either 

 a vestigial portion, or the precursor of a more robust mandibular symphysis, as this flange 

 was often observed to grade smoothly anteriorly into the symphysis. As well, the flange 

 is generally absent in the monachines, which, on the whole, possess a more robust 

 symphysis (pers. obs.). 



The distribution of the flange here closely matches that listed by King (1972, 1983). It 

 appears to be an apomoiphic condition shared by all phocines internal to Halichoerus, 

 except for Phoca largha, but including Histriophoca. It was also independently obtained 

 in Lobodon, but not consistently in Odobenus, which, like Monachus monachus, was 

 polymorphic for this trait. 



Forelimb (17 characters) 

 Post-cranial material has only sparingly been used to elucidate the systematics of the 

 phocids. Only King (1966) and Wyss (1988a) have used such material to any degree. This 

 reflects a number of factors. First, the comparative complexity of the mammalian skull 

 yields a disproportionately high number of (obvious) characters. As well, there is a 

 tendency for skins and skulls to be preferentially preserved over post-cranial material for 

 mammals in many museum collections. Often, mammalian taxa are represented only by 

 cranial material, making the inclusion of post-cranial material impossible in a practical 

 sense. Finally, when post-cranial material has been preserved, it is usually disarticulated, 

 making identification of the smaller isolated elements difficult and less desirable for study. 

 Hendey & Repenning (1972) consider many phocine post-cranial features to be primitive, 

 an interpretation also implied by Wyss (1988a). Within the phocids, the generally good 

 diagnostic value of the humerus has been noted (Ray 1976a; de Muizon & Hendey 1980). 

 153) relative size of scapular spine: 0 = reduced to prominent acromion; 1 = medium; 2 

 = prominent (King 1966; Wyss 1988a). 



The reduction of the scapular spine (both in length and height) in most monachines was 

 initially noted by King (1956, 1966). However, Wyss (1988a) correctly observed that the 

 spine exhibits three morphologies within the phocids: a prominent form in the phocines 

 where it extends virtually the full dorsoventral length of the scapula, the reduction to a 

 knob-like acromion in the lobodontines, and an intermediate condition in Mirounga spp. 

 and Monachus spp. Although Wyss (1988a) hesitantly equated this intermediate 

 morphology with the phocine pattern, we have chosen to leave it separate. Among the 

 outgroups, a reduced spine occurs only in ursids (Davis 1964) and the otarioids (Wyss 

 1988a). Wyss (1988a) has taken this distribution to indicate that a reduced spine is 

 primitive for the pinnipeds [assuming an ursid outgroup; see Wyss (1987)]. 

 A prominent scapular spine is plesiomorphic among the Caniformia and largely retained 

 throughout, including Ursus. The intermediate condition only appears in Odobenus, 

 Mirounga spp., and polymorphically with state 2 in Zalophus. This could arise through 

 parallel evolution (DELTRAN optimization), but may also indicate a synapomoiphy of 



