True seals

Until recently, seals were thought to have evolved from sea lions and walruses. However, recent evidence seems to contradict this.

An excerpt from the article 18 facts about True seals
According to the latest research, seals appear to have descended from a common ancestor - a mammal called Enaliarctos, which inhabited Earth from 24 to 22 million years ago. The animal was related to weasels and bears.