110 



tendencies thereto (Mirounga spp. and Monachus schauinslandi), the foramina apparently 

 coalesce in Odobenus, leading to the unique possession of a single midline foramen. 



61) reduction of incisive foramina: 0 = absent; 1 = present (Allen 1887). 



As noted in the previous characters dealing with the incisive foramina, three phocids, 

 Mirounga angustirostris, Mirounga leonina, and Monachus schauinslandi, convergently 

 share (between the two genera) the apomorphic tendency towards the absence of the 

 incisive foramina. This loss appears to be the extreme outcome of another apomorphic 

 tendency: the gradual closing over of the foramina by the bones of the hard palate. This 

 latter tendency is convergently displayed to various degrees in four monachine genera 

 (Hydrurga, Leptonychotes, Mirounga, and Monachus). Hydrurga, Leptonychotes (albeit 

 both are polymorphic for this trait), and Monachus monachus display a very early stage 

 in which the foramina are only partially covered over. Allen (1887) described a similar 

 condition in Monachus tropicalis, but this was not observed here. In Mirounga spp., this 

 process has advanced to the point so that the foramina are completely covered over, with 

 only a pair of depressions laying evidence to their prior existence. Finally, Monachus 

 schauinslandi displays the advanced condition where even the depressions are filled in 

 and the foramina can be said to be truly absent. It should be noted that this is not a true 

 developmental series, but isolated glimpses in three parallel ones, as these taxa are not 

 each other's closest relatives. 



62) position of major palatine foramen relative to maxillo-palatine suture: 0 = anterior; 1 

 = on; 2 = posterior (Ridgway 1972). 



The plesiomorphic caniform condition for this character is generally agreed to be one 

 where the anterior openings of the major palatine foramen open on, or very closely 

 adjacent to, the maxillo-palatine suture (Wozencraft 1989; Bryant et al. 1993). This 

 plesiomorphic placement is constant within the various carnivoran families, excluding the 

 mustelids (Pocock 1921) and the pinnipeds (Wozencraft 1989). Many independent origins 

 of an apomorphic anterior positioning have been postulated: various mustelines (Pocock 

 1921; Bryant et al. 1993), the lutrines (and within each of the genera Lutra and Aonyx) 

 (van Zyll de Jong 1987; Bryant et al. 1993), all monachines except the fossil lobodontine 

 Homiphoca capensis (de Muizon & Hendey 1980), and Pagophilus (Ridgway 1972). The 

 only specific description of a posterior shift of the foramina is for Histriophoca (Ridgway 

 1972), although a tendency towards this has been noted for Pusa spp. in particular 

 (Chapskii 1955a) and most phocines in general (Bums & Fay 1970). 

 Here, an apomorphic anterior shift of the foramina unites Lutra with the pinnipeds. This 

 condition is retained by the hypothetical phocid ancestor and largely throughout the 

 monachines, with only Ommatophoca showing a reversal to the primitive condition (state 

 1 ). The phocines primitively reverse to the plesiomorphic condition, with Pagophilus and 

 Phoca vitulina separately redeveloping the anterior shift, and Erignathus uniquely deriving 

 the posterior shift. 



63) shape of maxillo-palatine suture: 0 = flat / square; 1 = rounded / triangular (Allen 

 1887). 



This and the following two characters deal with the outline of the palatine bones on the 

 palate. In addition to Allen's (1887) observation of a straight transverse suture in Monachus 



