Taxonomy and Evolution
The Ross seal shares a recent common ancestor with the other Antarctic seals, which are together known as the lobodontine seals. These include the crabeater seal (Lobodon carcinophaga), leopard seal (Hydrurga leptonyx) and Weddell seal (Leptonychotes weddelli). These species, collectively belonging to the Lobodontini tribe of seals, share teeth adaptations, including lobes and cusps useful for straining smaller prey items out of the water column. The ancestral Lobodontini likely diverged from its sister clade, Mirounga (elephant seals) in the late Miocene to early Pliocene, when they migrated southward and diversified rapidly in relative isolation around Antarctica. However, the only fossil Ross seals so far known date from much later, during the early Pleistocene of New Zealand.
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