13 



Atlantic Phoca vitulina 



c 



Pacific Phoca vitulina 



Phoca largha 

 Halichoerus 

 Pusa hispida 

 Pag op hi I us 

 Histriophoca 



Cystophora 

 Erignathus 



Leptonychotes 

 Hydrurga 

 Mirounga leonina 

 Monachus schauinslandi 



Otariidae 



Odobenidae 



Ursidae 



Fig.l: Phylogeny of the Phocidae according to (A) de Muizon (1982a), (B) Wyss (1988a), and (C) 

 Arnason et al. (1995). Adapted from de Muizon (1982a), Wyss (1987. 1988a). and Arnason et al. 

 (1995). 



supporting such a scenario (e.g., Wyss 1987; Wolsan 1993; Wyss & Flynn 1993; Berta & 

 Wyss 1994; Hunt & Barnes 1994). But within such a framework, Wyss (1987) held the 

 Otarioidea to be related by symplesiomorphies only, and instead proposed an Odobenus- 

 phocid clade with an otariid sister group. This arrangement has since become the dominant 

 view of pinniped phylogeny (e.g., Flynn 1988; Berta 1991; Cozzuol 1992; Wyss & Flynn 

 1993; Berta & Wyss 1994; Vrana et al. 1994). 



Similarly, most workers in this area now also accept the ursids to be the sister group of 

 the pinnipeds, although several morphological or immunological studies persist in 

 proposing a mustelid. and not ursid, ancestry (e.g., Arnason & Widegren 1986; 

 Miyamoto & Goodman 1986; Wolsan 1993). However, much of this discussion may be 

 moot. As Repenning & Tedford (1977) note, considerations of polyphyly are largely 

 dependent on the definitions employed. Additionally, both fossil and molecular evidence 

 indicate that the mustelid, ursid, and pinniped lineages were all diverging at about the 

 same time from the primitive arctoid stock (Sarich 1976; Wayne et al. 1989; C.A. 

 Repenning pers. comm.). Hence, any discussion of mustelid or ursid affinities for the 

 pinnipeds may be irrelevant as these two groups may not have truly existed at the time 

 of pinniped divergence. Thus, the whole question of pinniped ancestry may form part of 



