133 



to a gross external examination of the bulla, we have again relied upon the data in 

 Wozencraft (1989) for this character. Numerous authors have noted the inflated bulla of 

 caniforms (Howell 1928; Repenning 1972; Hunt 1974), and this condition is indicated 

 here to be plesiomorphic and prevalent for the group; only the lutrines and Zalophus lack 

 an inflated bullar chamber. This latter situation occurs either convergently in each species 

 (DELTRAN optimization), or as a synapomorphy of the lutrines followed by a reversal 

 to the primitive condition for the pinnipeds, with Zalophus independently obtaining state 

 0 (ACCTRAN' optimization). 



Bony tentorium and bony falx (5 characters) 

 Although the bony tentorium and the bony falx are found throughout the carnivores, their 

 potential systematic value has generally been ignored. Using characters from both features, 

 Nojima (1990) argued for a diphyletic origin of the pinnipeds, grouping the otarioids with 

 the ursids and the phocids with the mustelids. However, the common possession of an "A 

 Type II" bony tentorium between ursids, otarioids, and probably all mustelids, to the 

 exclusion of all phocids except Histriophoca and Pagophilus (Nojima 1990), renders this 

 conclusion somewhat doubtful. As well, Wyss (1987) discounts a phocid-mustelid pairing 

 based on tentorial characters due to the high variability of the bony tentorium throughout 

 the arctoids. 



118) contribution of parietal to bony tentorium: 0 = none / processus tentoricus absent; 1 

 = contributes (Nojima 1990). 



The bony tentorium is composed of two main elements projecting from the occipital and 

 from the parietal (processus tentoricus) (Nojima 1990). Among the caniforms, only 

 phocids, possibly exclusive of Histriophoca and Pagophilus, lack a processus tentoricus, 

 and hence lack a parietal contribution to the bony tentorium (Nojima 1990). Here, the 

 apomorphic lack of a parietal contribution to the bony tentorium is a synapomorphy of 

 the phocids. Furthermore, this condition is universal for the group, including Histriophoca 

 and Pagophilus. 



119) contribution of parietal to bony falx: 0 = none; 1 = contributes; 9 = bony falx absent 

 (Nojima 1990). 



As with the bony tentorium, the parietal also occasionally contributes to the bony falx. 

 Of those taxa where the bony falx is present (see character #121), Nojima (1990) indicates 

 a parietal contribution only in the otarioids and the ursids. In phocids, the bony falx is 

 derived exclusively from the occipital (Nojima 1990). This is largely borne out here. A 

 parietal contribution to the bony falx is plesiomorphic in caniforms, characterizing both 

 Canis and Ursus. Beyond this, the bony falx is initially absent before reappearing, albeit 

 with no contribution from the parietal, as a synapomorphy linking Lutra with the 

 pinnipeds. Within this group, a parietal contribution occurs independently in Zalophus 

 (possibly the otarioids as a whole; ACCTRAN optimization), Histriophoca, and Mirounga 

 angustirostris (possibly Mirounga spp. as a whole; ACCTRAN optimization). 



120) ventral extension of bony tentorium: 0 = does not approach floor of braincase; 1 = 

 approaches dorsal region of petrosal; 2 = approaches or contacts floor of braincase (Nojima 

 1990). 



