124 



indicates this to be the case solely for the canids. In the phocids, the general pattern is 

 for the paroccipital processes to be poorly developed, if not virtually absent, in the 

 phocines and well developed in the monachines. The exceptions are Erignathus and 

 Mirounga spp., which take on the characteristics of the opposite subfamily (Bryden 1971; 

 King 1972). The paroccipital processes of the otarioids are well developed, and are 

 confluent with the mastoid process via the petromastoid ridge (Howell 1928; Wozencraft 

 1989; see character #87). 



The lateral compression of the paroccipital processes is a synapomorphy linking the 

 lutrines and the pinnipeds. Several independent reversals to the primitive caniform 

 morphology of rounded processes occur within the pinnipeds: Zalophus, Mirounga 

 angustirostris, and the phocines internal to Cystophora (with Erignathus reversing again 

 to re-obtain the primitive pinniped condition). Paroccipital processes were entirely absent 

 only for Pusa caspica, although Pusa sibirica was polymorphic for this condition. 



92) size of paroccipital processes: 0 = small / not prominent; 1 = intermediate; 2 = large 

 / prominent; 9 = processes absent (pers. obs.). 



A reduction in the size of the paroccipital processes has only been indicated for the 

 phocines (exclusive of Erignathus), Mirounga spp., and various mustelids (including the 

 lutrines) among the caniforms (Turner 1848; Flower 1869; Bryden 1971; King 1972). The 

 observation that the paroccipital processes are apparently lost during ontogeny in Phoca 

 largha (Chapskii 1967) hints at their former presence in ancestral forms. Our observations 

 largely bear this out. Large processes are plesiomorphic for the Caniformia, before being 

 drastically reduced to state 0 in Martes, the lutrines, and the pinnipeds. The monachines, 

 exclusive of Mirounga spp., are generally characterized by medium-sized processes. This 

 occurs either as a synapomorphy of the lobodontines plus Monachus spp. (ACCTRAN 

 optimization), or only of Lobodon plus Monachus spp. (DELTRAN optimization). The 

 phocines largely retain small processes except for Cystophora and the clade of Erignathus, 

 Histriophoca, and Pagophilus, which independently derive medium-sized processes. 

 Reversals to large processes occurred only in Zalophus, Monachus schauinslandi plus 

 Monachus tropicalis, and possibly Hydrurga. Again, paroccipital processes were 

 consistently absent in Pusa caspica, and polymorphically so in Pusa sibirica. 



93) relationship between paroccipital processes and mastoid bone: 0 = separate; 1 = 

 adjacent / continuous; 9 = n/a - paroccipital processes absent (pers. obs.). 



In many taxa, we noted that the paroccipital processes were not distinct, isolated structures. 

 Other than contacting the auditory bulla (see character #85), the paroccipital processes 

 often graded into either the mastoid bone anteriorly (more common in forms with small 

 processes such as the Phocini), or the nuchal crest posterodorsally (see the following 

 character). With respect to the mastoid bone, the general distribution is for it to be 

 continuous with the paroccipital processes in Ursus, Martes, the otarioids, and the phocines 

 internal to Cystophora (except Pusa caspica which obtains state 9). This could arise 

 through parallel evolution in each of these taxa (DELTRAN optimization). However, the 

 polymorphism of Procyon and Lutra also allows for the situation whereby state 1 is 

 plesiomorphic for the arctoids (the condition for the caniforms being equivocal), which 

 the otarioids and phocines (minus Cystophora) reverse back to after state 0 arises as a 

 synapomorphy of the lutrines plus the pinnipeds (ACCTRAN optimization). 



