95 



in relation to other phocids and not to the Caniformia as a whole. As Wozencraft (1989) 

 gave no criteria for distinguishing long versus short rostra, our observ ations deal strictly 

 with the placement of the canal opening. These observations and the resulting polarity 

 assessment do coincide with those of Wozencraft (1989). An anterior placement is shared 

 primitively only by Canis and Ursus, while all remaining taxa are united by the 

 apomorphic ventral (or posterior) placement. 



Orbit and zygomatic arch (35 characters) 

 The orbital region in the pinnipeds, and especially in the phocids. yields a number of 

 diagnostic features. Many of these are correlated with the proportionately narrow 

 interorbital region of the pinnipeds. Although the distribution for most of the characters 

 is well known and well referred to in the literature, very few of these traits have been 

 examined in a systematic context for the phocids. 



22) swelling of maxilla anterior to zygomatic arch: 0 = absent: 1 = present (Burns & Fay 

 1970: King 1972) (Fig.19). 



Initially, this character dealt with the formation of a "shoulder" by a dorsolateral projection 

 of the maxilla and jugal in the anterior wall of the orbit. King (1972: her Fig. 18) described 

 such a shoulder in Cystophora (also Reeves & Ling 1981: Kovacs & Lavigne 1986) and 

 Miwunga as a mechanism to displace the eyes laterally to see around the i independently 

 derived) nasal appendages. However, this shoulder was not readily apparent during any 

 of our observ ations and instead, a swelling of the maxilla anterior to the zygomatic arch 

 was noted for many species. This swelling is noted to be typical of the phocines (Burns & 

 Fay 1970; King 1972). although it is expressed by all phocids to some degree (Burns & 

 Fay 1970). It has been attributed to a lateral expansion of the maxilloturbinals. designed 

 to counteract their constriction by the reduced interorbital region (King 1972) and/or as 

 an adaptation to efficiently warm inspired air in response to the cooling environment of 

 the late Tertiary and current high altitude habitats (de Muizon & Hendey 1980: Mills & 

 Christmas 1990). The lack of a swelling in the lobodontines apparently arises from their 

 accommodation of the expanded maxilloturbinals within a dorsoventrally expanded nasal 

 cavity (de Muizon & Hendey 1980). This likely represents a secondary solution to the 

 problem (the swelling being the first), as certain populations of the fossil lobodontine 

 Homiphoca capensis are noted to possess a phocine-like swelling (de Muizon & Hendey 

 1980). 



Here, a truly distinctive swelling (the apomorphic condition) was present only for Phoca 

 vitidina and Pusa spp.. although most phocines are polymorphic for this trait. It also 

 appears in the lutrines. either independently in each (DELTRAX optimization), or as a 

 synapomorphy which is later lost in the pinniped ancestor (ACCTRAN optimization). 



*23) distinct preorbital process of maxilla: 0 = absent: 1 = present (Burns & Fay 1970) 

 (Fig.20). 



With recoding, this character was included in character #24. 



24) size of preorbital process of maxilla: 0 = small: 1 = medium: 2 = large: 9 = absent 

 (Burns & Fay 1970; pers. obs.) (Fig.20). 



