Named By: Fraas - 1904.
Classification: Chordata, Mammalia, Cetacea, Archaeoceti, Protocetidae.
Species: P. atavus (type).
Size: 2.5 meters long.
Known locations: Egypt. - Mokattam Formation.
Time period: Early Lutetian of the Eocene.
Fossil representation: Single specimen.
change from a terrestrial to more aquatic life that began with Pakicetus
continued with the further developments of
Protocetus. The front limbs still had webbed
toes, but the rear
limbs were already greatly reduced in size to the point of them being
vestigial. The caudal vertebrae towards the end of the tail also
hint towards the development of a tail fluke that would have provided
much greater push through the water than its ancestors had. The
nostrils of Protocetus were also faced further back
on the snout for
easier breathing from the water surface. The ears are also best
developed for working while underwater.
Protocetus was still a dedicated predator with jaws shaped into a long thin snout, ideally suited for quick opening while submerged since the narrow jaws would experience far less resistance as they moved through the water. The teeth at the frontal portion of the jaws were more suited to prey capture while the teeth at the back were more suited for slicing. Just like with terrestrial predators the back of the mouth is the best position for the actual processing teeth since they gain more benefit from being placed nearer the fulcrum of the jaw articulation because of the more direct force from the jaw closing muscles.
Protocetus is so far only known from earlier in the Eocene, but by the time the Eocene ended even better developed whales such as Dorudon, Zygorhiza and of course the gigantic Basilosaurus were all swimming and hunting in the world’s oceans.
- Neue Zeuglodonten aus dem Unteren Mitteleocän vom Mokattam bei Cairo. - Geologische und Palaeontologische Abhandlungen 6(3):199-220 - E. Fraas - 1904.