Pakicetidae

Skull of Pakicetus

• South Asia

The Pakicetidae are a group of extinct early representative of the whales who still had limbs that enabled them to life on land. They lived in the Eocene in South Asia and will enable important conclusions on the evolution. There are three genera known: Pakicetus, Nalacetus and Ichthyolestes.

See also: Basilosaurus, Ambulocetidae, Dorudontidae

General

The Pakicetidae were very similar in physique and were about to wolf fox - sized animals that were externally detect little resemblance to today's whales. They had four typical mammal limbs that were suitable for locomotion on land. Some adjustments showed, however, that the animals could have at least temporarily lived in shallow water, such as a thickening of the bone, which could have reduced the lift. The eye sockets were high up on the head, the nostrils were located on the incisors. Belonging to the whales can be seen ( in the arrangement of cusps ) in the construction of the ears, the cranial cavity and the molars.

The Pakicetidae lived in the Eocene, about 50 million years ago. Fossils are known from Pakistan and India, and it is believed that in this region took place the evolution of whales.

System

Apart from the poorly preserved Himalayacetus the Pakicetidae are the oldest remains of whales. Later formed groups like the Ambulocetidae, Rodhocetus or Remingtonocetidae already indicated much stronger adaptations to aquatic life.

Importance for research

The discovery of Pakicetidae has helped to better explore the relationships of whales. An earlier sometimes suspected origin of whales from the Mesonychia could be refuted. Rather, could be recognized that the early whales still a ankle with a double- rolled joint surface had. This feature has long been considered the exclusive feature of the Artiodactyla, thus the close relationship between the two taxa could be substantiated morphologically. Molecular genetic studies had previously demonstrated this close relationship, according to the most common theory today cloven-hoofed animals and whales are summarized as Cetartiodactyla because some cloven-hoofed animals such as hippos are more closely related to whales than with the other mammals.