Day 08: Fossils
| Dorudon atrox
The Dorudon atrox was a fully-aquatic cetacean found in the Birket Qarun and Gehannam Formations. The D. atrox was medium-sized, around five meters in length. It is believed that the hind legs were too small to have supported its weight and the front limbs were modified flippers so the D. atrox was never able to walk on land. Instead, they swam in warm, shallow seas. The main difference between this animal and other primitive terrestrial mammals was the hearing system which was adapted for effective sound perception under water.
| MOERITHERIUM
The moeritherium was a primitive mammal closely related to today’s elephants. However, it more closely resembled tapirs with short, strong legs, a short tail, and flat-hoofed toes. The eyes were set very far forward and the nasal openings could be found on the upper side of the skull. It is speculated that the moeritherium did not possess and elephantine trunk. The front incisors developed in the upper and lower jaws and they represent the development process of today’s elephant tusks. The moeritherium could be found in marshy regions.
| BASILOSAURUS
The basilosaurus is classified as a whale, but it is not the ancestor of modern whales. It is also named as if it is a reptile (-saurus), but it was later discovered to have been a marine mammal. The basilosaurus grows to about 15 meters in length and was one of the largest known animals of its day. The vertebrae of the backbone was very elongated and the narrow skull was relatively small. Although it had flippers, it had an elbow joint that allowed it to pivot them like a seal of today would. This helped the basilosaurus chase prey into holes and crevices. Like the Dorudon atrox, it could be found in warm, shallow water.