150 



The appearance of the supinator ridge among the caniforms appears to be much more 

 complex than indicated by Wyss (1988a). The polarity is equivocal at the level of the 

 Caniformia due to the absence of the ridge in Canis. However, a similar absence in the 

 domestic cat, Felis domestica (Crouch 1969), increases the likelihood that this is the 

 plesiomorphic condition. The arctoids derive a medium-sized ridge, which the phocids 

 reduce somewhat (state 0). This weak supinator ridge is largely retained for the 

 monachines, with the clade of Monachus schauinslandi and M. tropicalis losing the ridge 

 completely. A strongly developed ridge is unusual among caniforms, being limited to the 

 phocines exclusive of Cystophora, with a parallel appearance in Procyon. Pusa caspica 

 uniquely derives state 1 among phocids. 



* 158) deltopectoral crest on humerus: 0 = absent; 1 = present (Wyss 1988a). 

 With recoding, this character was included in characters #159 and 160. 



159) relative length of deltopectoral crest on humerus: 0 = less than or equal to one-half 

 length of humerus; 1 = greater than one-half length of humerus; 9 = absent (Wyss 1988a). 

 In all pinnipeds, the pectoralis muscle is quite prominent, resulting in a strengthening of 

 its insertion point on the humerus (Howell 1928; Bryden 1971; Hendey & Repenning 

 1972). Hendey & Repenning (1972) distinguished two main patterns for this strengthening. 

 In phocines, the pectoralis inserts only on the proximal half of the humerus, resulting in 

 a deltopectoral crest that extends towards the enlarged lesser tubercle proximally, and is 

 quite robust at its distal end. The crest extends to slightly less than halfway along the 

 length of the humeral shaft before ending abruptly in a shaip overhang. In contrast, the 

 insertion of the pectoralis in monachines is extended distally on the humerus, resulting in 

 a deltopectoral crest that is two-thirds to three-quarters of the length of the humerus and 

 grades smoothly into its shaft (Hendey & Repenning 1972; Wyss 1988a). Leptonychotes 

 apparently shows a disposition towards the phocine pattern (de Muizon 1982a). Otarioids 

 tend towards the monachine pattern (Hendey & Repenning 1972; Wyss 1988a), leading 

 Wyss (1988a) to postulate it as plesiomorphic for the pinnipeds. This character examines 

 one aspect of this morphology, the length of the crest, while the following character looks 

 at the merging of the crest with the humeral shaft. 



The current character presents a rather uncertain evolutionary pathway, although the 

 distribution of the states is well marked. The phocine pattern is present in all phocines, 

 with additional appearances in Canis, Procyon, and Hydrurga. Meanwhile, the monachine 

 pattern is found in those monachines internal to Hydrurga, Lutra, and the otarioids. 

 Enhydra and Mirounga spp. are polymorphic for these two states. A distinct crest is 

 uniquely absent in Martes. However, this distribution has the effect of rendering the 

 polarity at the level of the Caniformia equivocal. This situation may persist through to the 

 phocids, with the different morphologies arising independently within the family 

 (DELTRAN optimization). Another scenario has the monachine pattern as a synapomorphy 

 of the arctoids, before the phocine pattern is derived ancestrally for the phocids and 

 retained into the basal members of each subfamily at least (ACCTRAN optimization). 



160) merging of deltopectoral crest to shaft of humerus: 0 = smooth; 1 = abrupt; 9 = 

 absent (Wyss 1988a). 



