143 



trend for all phocids except Hydrurga and Lobodon (de Muizon & Hendey 1980). 

 Unfortunately, a coding based on the first and last postcanines is limited to the phocids 

 only, due to the generally different homology between the postcanines of the phocids and 

 the outgroups (very few of which possess a 4/1 postcanine formula). Thus, the 

 inapplicability of this and the following character for the outgroups (including the 

 otarioids, in order to avoid biasing the results in favour of a monophyletic Pinnipedia) 

 results in their polarities being determined to some degree by the outgroup relations 

 entailed by the remaining characters. 



The primitive condition in phocids is for all upper postcanines to be subequal in size, a 

 state maintained ancestrally in each subfamily. The phocines internal to Cystophora are 

 largely characterized by a reduction of the first postcanine only; only Histriophoca (state 

 0) and Pusa sibirica (state 3) deviate from this. Among monachines, there exists a tendency 

 to decrease both the first and last postcanines in those taxa internal to Hydrurga [as 

 described for Monachus tropicalis by Allen (1887)]. Ommatophoca, and possibly 

 Monachus monachus, retain primitive subequal postcanines. Mirounga spp. is uniquely 

 diagnosed by state 4, with the last postcanine typically being the enlarged tooth. A 

 reduction of only the last postcanine was never consistently present at the species level. 



142) relative size of lower postcanines: 0 = all subequal; 1 = #1 (PM,) noticeably smaller 

 than rest, which are subequal: 2 = #5 (M x ) noticeably smaller than rest, which are subequal; 

 3 = #1 and #5 noticeably smaller than rest, which are subequal; 4 = #1 and/or #5 noticeably 

 larger than rest, which are subequal; 9 = n/a - postcanine homology uncertain (Allen 1887; 

 Scheffer 1960). 



This character presents much the same distribution as the previous one [and as indicated 

 by Allen (1887) and Scheffer (1960) for Monachus tropicalis and Histriophoca 

 respectively]. As with the upper postcanines, subequal lower postcanines represent the 

 ancestral state for the phocids and both subfamilies. The phocines, excluding Cystophora, 

 now universally share a reduced first postcanine, as does the clade of Lobodon plus 

 Monachus spp. among monachines. The reduction of both the first and last postcanines is 

 here limited to Leptonychotes, Mirounga angustirostris (possibly as a synapomorphy of 

 Mirounga spp.; ACCTRAN optimization) and Monachus tropicalis. States 2 and 4 never 

 appeared consistently at the species level. 



143) tendency to single-rooting of upper postcanines: 0 = absent; 1 = present (de Muizon 

 1982a). 



A tendency towards having single-rooted postcanines was noted exclusively among 

 phocids for Halichoerus by de Muizon (1982a). This tendency is also strongly present, 

 and apparently developing, in otariids (Mivart 1885; King 1983). However, this character 

 might have a larger distribution contingent on the definition of the term "tendency". In 

 phocids, upper postcanine #1 is invariably single-rooted, #5 double-rooted, and #2 to #4 

 often transitional and variable, a pattern observed in Histriophoca by Scheffer (1960). 

 When postcanine #5 is single-rooted, this is more often due to its reduced size (see 

 characters #141 and 142), than to any trend towards single-rootedness of the postcanines. 

 Therefore, if a true tendency to single-rootedness is present, it should affect the inner 

 postcanines, and will be scored as being present if one or more of these postcanines is 

 consistently single-rooted within a species. 



