|
|
Reconstruction of Basilosaurus cetoides (top) and Zygorhiza kochii (not to scale). There are several inaccuracies in this old reconstruction (Kellogg, 1936), such as the exact number of vertebrae and the shape of the forelimbs. Discovery of new specimens has made it possible to correct these.
Basilosaurids and dorudontids lived in the late Eocene, approximately 35 and 41 million years ago. They are mainly known from the eastern United States and from Egypt, but were probably worldwide in their distribution. Basilosaurids were enormous (possibly up to 60 feet long) and had snake-like bodies. They had a tailfluke, but it is not clear whether that was the main propulsive organ. Dorudontids were proportionally more like dolphins. Both basilosaurids and dorudontids had complete hindlimbs, that included a mobile knee and several toes. However these extremities were tiny, so small that they were certainly not important in aquatic propulsion.
All pictures on Dr. Thewissen's pages are public access, although the source must be identified in publication.
Ambulocetidae
| Basilosaurids and
Dorudontids | Bibliography | Hearing
| India |
Locomotion | Mysticetes
| Odontocetes | Osmoregulation
| Pakicetidae |
Pakistan | Protocetidae
| Remingtonocetidae | Whale
| Whale Origins!