Pakicetus

Pakicetus is an extinct early cetacean that lived in the Eocene and is known from fossils found in Pakistan. Its anatomy links land-dwelling mammals with later whales.

Cetacea: Cetacea is the mammalian order comprising whales, dolphins, and porpoises. Pakicetus belongs to this order despite retaining a largely land-adapted body.
Pakicetidae: Pakicetidae is a family of early whales known chiefly from Eocene fossils in Pakistan and India. Pakicetus is the namesake genus of this family of terrestrial early cetaceans.
Kuldana Formation: The Kuldana Formation is a geological unit in Pakistan that preserves Eocene fossils, including early whales. Its deposits yielded key Pakicetus fossils.
Blue whale: The blue whale is the largest living animal and a fully aquatic baleen whale. Its streamlined aquatic body contrasts with Pakicetus's terrestrial limbs and locomotion.
Archaeoceti: Archaeoceti is an informal grouping of extinct early whales, including forms ancestral to modern cetaceans. Pakicetus is among the earliest known members of this whale group.
Ambulocetus: Ambulocetus is an early whale from the Eocene of Pakistan, adapted for movement on land and in water. It represents a more aquatic body form than Pakicetus in the same broad evolutionary transition.
Kala Chitta Range: The Kala Chitta Range is a mountain region in northern Pakistan with Eocene sedimentary rocks. Pakicetus fossils were discovered in this region's Eocene deposits.
Hippopotamidae: Hippopotamidae is the mammal family containing hippopotamuses, the closest living relatives of cetaceans. Hippos are living relatives, whereas Pakicetus records an early stage of the cetacean lineage.
Mesonychia: Mesonychia is an extinct group of hoofed mammals once proposed as close relatives of whales. Pakicetus was once linked to mesonychians, but ankle anatomy supports an artiodactyl relationship.
Rodhocetus: Rodhocetus is an early whale from the Eocene of Pakistan with adaptations for swimming. Its reduced limbs and more aquatic anatomy show changes beyond those seen in Pakicetus.

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