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Protocetus
''Protocetus atavus'' ("first whale") 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 Gebel Mokattam near Cairo, Egypt.
==Description==
''Protocetus'' had a streamlined, whale-like body around long, but was relatively primitive in many respects; it still had small hind flippers, and its front flippers had webbed toes. Its jaws were long and lined with deadly teeth. The shape of the bones in the tails suggests that it may have evolved tail flukes, like those of modern whales, and, while it did not have a true blowhole, the nostrils had already begun to move backwards on the head.
Unlike its more primitive predecessor ''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.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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