Linked from
The 44 pages that link to Cetacea, each with the reason it gives.
PaleogeneBroader topic: Whales evolved from land-dwelling mammals during the Eocene.
BlubberBroader topic: Many cetaceans rely on blubber for insulation and energy storage.
CetartiodactylaBroader topic: Cetaceans are nested within the broader cetartiodactyl clade.
ArtiodactylBroader topic: Cetaceans are living artiodactyls adapted completely to aquatic life.
PlacentaliaBroader topic: Cetaceans show how placental mammals adapted to fully aquatic life.
MammalogyBroader topic: Cetaceans show how mammal anatomy can adapt to fully aquatic life.