Dorudon

The Department of Geology

The School of Earth, Society, and Environment

College of Liberal Arts and Sciences

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Correct! The presence of hind limbs on whales indicates that whales evolved from animals that lived on land! Open the packet labeled '1' and check the contents, you should have: A Dorudon 'fossil' An image of Dorudon vestigial legs An image of Dorudon teeth A Pachyaena 'fossil' An image of Pachyaena teeth We have NO fossils of modern whales earlier than about 25 million years ago (“mya”= millions of years ago). However, for many years, we have been finding a number of fossils of various primitive whales (called archaeocetes) between 25 and 45 million years old (during the Oligocene and Eocene), and somewhat different from modern whales (e.g. with very distinctive teeth). An example of these early whales is Dorudon. Dorudon was found in Egypt from rocks that are about 36 million years old. Place the fossil picture strip of Dorudon at about 36 mya on your timeline. Look at the vestigial rear legs of Dorudon. Are they more formed or less formed than those of the sperm whale? As more fossils have been discovered from the early Eocene (55 to 34 mya), we searched for a land mammal from which whales most likely evolved. Pachyaena is an example of a group called Mesonychids, and lived approximately 55 mya. Mesonychids also had hooves, suggesting that whales may be related to other animals with hooves, like cows, horses, deer and pigs. Place the Pachyaena fossil at 55 mya on your timeline.

Compare the fossil of Pachyaena to the fossil of Durodon, what feature is similar between the two animals (answer with one word)? Click Here to Answer

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mlc7 (at) illinois.edu