Abstract
The hypothesis that pinnipeds have a common origin gained support during the 1980s in discussions focused on the systematics of the group. However, the limited knowledge of the anatomy of several species and the frequent variation in several character states make it difficult to clarify the phylogenetic relationships of pinnipeds. Our purpose was to review the anatomical characters of the syncranium and dentition used in phylogenetic analyses by studying the otariids Otaria byronia (n=25) and Arctocephalus australis (n=48). Some interpretations of characters presented in the literature were found to be questionable, notably: (1) shape and
Highlights
Since the 19th century, there has been controversy concerning the origin, evolution and phylogenetic relationships of pinnipeds
A diphyletic origin for the Pinnipedia was the prevailing hypothesis (Otariidae and Odobenidae would share a common ancestor with the Ursidae; whereas Phocidae would share a common ancestor with the Mustelidae (MITCHELL; TEDFORD, 1973; TEDFORD, 1976)
This scenario changed during the second half of the 1980s (WYSS, 1987; 1988a; 1988b; 1989), especially due to the reinterpretation of diagnostic characters, studies of the postcranial skeleton (WYSS, 1988b; WYSS, 1989) and discovery of new fossil species (between otarids are still controversial (BERTA), 1991; 1994; DEMÉRÉ; BERTA, 2001; 2002; 2005; DAVIS et al, 2004; UHEN, 2007), which supported the idea of an arctoid common ancestor for the Pinnipedimorpha
Summary
Since the 19th century, there has been controversy concerning the origin, evolution and phylogenetic relationships of pinnipeds. A diphyletic origin for the Pinnipedia was the prevailing hypothesis (Otariidae and Odobenidae would share a common ancestor with the Ursidae; whereas Phocidae would share a common ancestor with the Mustelidae (MITCHELL; TEDFORD, 1973; TEDFORD, 1976) This scenario changed during the second half of the 1980s (WYSS, 1987; 1988a; 1988b; 1989), especially due to the reinterpretation of diagnostic characters, studies of the postcranial skeleton (WYSS, 1988b; WYSS, 1989) and discovery of new fossil species (BERTA, 1991; 1994; DEMÉRÉ; BERTA, 2001; 2002; 2005; DAVIS et al, 2004; UHEN, 2007), which supported the idea of an arctoid common ancestor for the Pinnipedimorpha. Árnason et al (2006), using molecular characters, showed Pinnipedia as a monophyletic clade, considering the Otariidae+Odobenidae as a basal divergence inside the group, followed by the Phocidae
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