Which unique family is the modern walrus the sole survivor of?

Odobenidae

The walrus belongs exclusively to the family Odobenidae, distinguishing it genetically and morphologically from the other two modern pinniped families. Odobenidae represents an ancient lineage that diverged early from the ancestors of true seals (Phocidae) and sea lions (Otariidae). The fact that *Odobenus rosmarus* is the only extant member signifies a severe pruning of the family tree, likely due to dramatic environmental shifts, such as the cooling climate and the contraction of warmer seas where its diversity once flourished during the Miocene epoch. This singularity highlights the specialized nature of the group that managed to adapt successfully to the demanding, seasonally frozen Arctic habitat.