Protocetus
Protocetus atavus is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago. The first discovered protocetid, Protocetus atavus was described by based on a cranium and a number of associated vertebrae and ribs found in middle Lutetian Tethyan marine limestone from the Mokattam Formation at Gebel Mokattam near Cairo, Egypt.
Description
Protocetus are believed to have had a streamlined, whale-like body around long, but was probably primitive in some respects.Many protocetids possessed well developed innominates and hind limbs, often attached to the backbone with a sacrum. Protocetus are known to have had at least one sacral vertebrate, and likely possessed hind limbs and webbed toes. Despite previous proposals to the contrary, the current general consensus is that Protocetus and other protocetids lacked tail flukes.
The head of Protocetus measured about 0.6 meters long. The jaws were long and lined with sharp teeth. While it did not have a true blowhole, the nostrils were placed further back on the head than in most land mammals. Unlike the more primitive Pakicetus, the structure of the ears suggests that Protocetus was able to hear properly underwater, although it is unlikely that it could echolocate. Similarly, it retained sufficient olfactory apparatus to have a good sense of smell, although it probably relied more on its eyesight to find prey.