Evolution and systematics

The most recent view is that all pinnipeds (walruses, true seals, and eared seals) had a single evolutionary origin. However, this should be considered a provisional view because the evolutionary sequences for these three groups are still incompletely known. Pinnipeds are most closely related to the arctoid carnivores, especially bear-like and racoon-like mammals. The current debate is whether walruses are more closely related to the true seals or the eared seals. The eared seals arose in the late early Miocene (20-15 million years ago) in the North Pacific. From there they moved south and diversified in the Southern Hemisphere where most species now live. Fur seals are considered to be older than sea lions. Cal-lorhinus (northern fur seal) is the genus having the oldest lineage. Otariids are not perfectly separable into sea lions and fur seals; the Afro-Australian fur seal is intermediate between the two in behavior and anatomy.

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