185 



Atlantic Monachus spp. However, if M. schauinslandi is really the sister group to the 

 remaining monk seals [as advocated by Repenning & Ray (1977) and Wyss (1988a)], then 

 its migration around Cape Horn into the Pacific becomes more plausible, given a 

 terminally placed Monachus. 



The situation for the phocines is even less clear, with the phylogeny indicated here for 

 this subfamily supporting (or at least not outright contradicting) each of the two major 

 hypotheses presented above. Both do possess problems, however. Monophyly of Pusa spp. 

 cannot be assured here, as required for the dual Paratethyan-North Atlantic origin 

 hypothesis, while the relatively basal position of Phoca largha, an exclusively western 

 Pacific species, is problematic for a mass origin from the North Atlantic alone. Another 

 possibility might be that only Cystophora and Halichoerus originated from the North 

 Atlantic, while the remaining, monophyletic forms all arose from the isolated Paratethyan 

 stock. Support for this hypothesis comes from the fact that only Cystophora and 

 Halichoerus, together with Pagophilus, are normally found exclusively in the Atlantic. 

 [The Atlantic-only distribution of Pagophilus might have arisen as a result of a recent 

 split in the Arctic basin of an ancestral lineage into the sister species Histriophoca and 

 Pagophilus, as envisaged by Davies (1958b).] Again, the reasonably basal position of 

 Phoca largha is problematic, as this species would presumably be derived from the original 

 Pusa-like inhabitants of the Paratethyan, whereas the reverse in indicated here. However, 

 the Pusa-like nature of the Paratethyan fauna might be overstated due to the predominance 

 of its fossil material. Other phocine lineages (primarily Phoca-like forms) are also 

 represented in the Paratethyan fauna (Grigorescu 1976), and Phoca largha (as well as the 

 remaining non-pusids) might have originated from one of them. 



Although many of the possible biogeographical options listed here involve long distance 

 migrations for several species, comparable movements for several extant pinniped species 

 are known (see Scheffer 1967; Ray 1976a). These examples include stray individuals that 

 have either been found in presumably less desirable habitats (e.g., too warm for normally 

 pagophilic species, or too cold for the less pagophilic ones), or whose presumed travel 

 route would require traversing such habitats. 



Future directions 



The study of the evolutionary biology of the phocids faces two major obstacles at the 

 moment. Firstly, the phylogenetic relationships within the Phocini (with or without 

 Erignathus) continue to be problematic. In all truth, the pattern that we advocate here is 

 merely one in a long line of hypotheses (e.g., Chapskii 1955a; McLaren 1966, 1975; 

 Burns & Fay 1970; de Muizon 1982a; Arnason et al. 1995; Mouchaty et al. 1995; Perry 

 et al. 1995). More research is needed in this area with techniques better suited to such 

 low level analyses. 



One such technique involves the use of molecular data which, paradoxically, has been 

 used more up to now to elucidate the position of the phocids within the pinnipeds (e.g., 

 Sarich 1969a, 1969b, 1975; Arnason 1974, 1977; Haslewood 1978; de Jong 1982; de 

 Jong & Goodman 1982). Instead, the internal phylogeny of the phocid seals has been 

 elucidated largely through the use of (traditional) morphological data. Some initial work 



