LOCOMOTION

The real fossil bones of the walking and swimming whale, Ambulocetus natans, are spread out in this picture with a sledgehammer for scale. The skeleton was about 12 feet long and is about 49 million years old. It was found in Pakistan.

A high-resolution image can be found at URL: http://www.neoucom.edu/Depts/Anat/publ.html

Many modern groups of mammals have representatives that are amphibious to varying degrees. These living mammals are good models to study locomotion in extinct whales. The modes in which otters and their relatives (mustelid carnivores) swim give a lot of insight into the evolution of whale swimming. One of the more terrestrial mustelids is the mink, which paddles with all four feet while swimming. River otters paddle mainly with their hind limbs and also propel themselves by making undulating movements with their vertebral column and tail. Seaotters swing their enormous feet through the water. The giant South American freshwater otter swims by dragging its tail up and down through the water. The tail is enlarged and flattened into a paddle, somewhat similar to the fluke of a whale.

Ambulocetus is an amphibious whale for which the skeleton of the fore and hindlimb is nearly completely known. This makes it possible to analyze how it moved on land and in water. Using otters as models Dr. Thewissen and Dr. Frank Fish determined that Ambulocetus probably swam like a modern otter, swinging its hindlimbs through the water.

All pictures on Dr. Thewissen's pages are public access, although the source must be identified in publication.

Back to Dr. Thewissen's Home Page

Back to Research Program Page