152 



process is a synapomorphy of the arctoids (the polarity being equivocal for the caniforms) 

 and is consistently found in Ursus, Martes, Enhydra, and Lutra. 



163) general morphology of metacarpal shaft: 0 = no lateral shaft ridges; 1 = lateral shaft 

 ridges (M.A. Cozzuol pers. comm.) (Fig. 23). 



M.A. Cozzuol (pers. comm.) kindly pointed out that the metacarpals in some phocines are 

 marked by small longitudinal ridges on each side of the distal palmar surface. However, 

 at best, many phocine taxa are only polymorphic for this plesiomorphic caniform feature. 

 The loss of these ridges describes a synapomorphy of Martes, the lutrines, and the 

 pinnipeds, with the tendency towards regaining this feature only appearing consistently in 

 Lutra and Pusa caspica. 



164) general morphology of metacarpal head: 0 = smooth; 1 = "palmar" ridges present 

 (King 1966; Wyss 1988a) (Fig.23). 



Character #18 of Wyss (1988a) describes a suite of features related to the morphology of 

 the metacarpal-phalangeal articulation. We have chosen to subdivide Wyss's (1988a) 

 character into its component parts (this character, characters #165 and 166). Wyss (1988a) 

 described his first component, the longitudinal "palmar" ridge, as dividing the distal and 

 palmar surfaces of the metacarpal head (also King 1966). If we have in fact observed the 

 same feature intended by Wyss (1988a), we would amend his definition to something more 

 akin to the keeled heads of Berta & Ray (1990): a longitudinal ridge (or keel) on the distal 

 metacarpal head running between the palmar and anti-palmar surfaces. Among caniforms, 

 this "palmar" ridge is absent only in otarioids and monachines (King 1966; Wyss 1988a), 

 which Wyss (1988a) interprets as a synapomorphy of the pinnipeds, with a reversal to the 

 primitive carnivore condition (state 2) by the phocines. However, our observation of 

 "palmar" ridges among the otarioids renders the outright lack of any such ridges as a 

 synapomorphy solely of the monachines as a whole (ACCTRAN optimization), or of the 



#164 



#163 



• > 



Fig.23: Ventral view of the third metacarpal of a canid (Canis familiaris) 

 illustrating selected characters (indicated by their number; see Character 

 Analysis) of this element. Distal is towards the top of the page. Adapted from 

 Miller (1962). 



