Where does Ambulocetus belong on the timeline?

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The Department of Geology

The School of Earth, Society, and Environment

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Correct! Ambulocetus has more developed hind limbs than Basilosaurus, but less developed hind limbs than Pakicetus. suggesting that it is intermediate in age. Ambulocetus fossils are about 49 million years old. Place your Ambulocetus fossil at 49 mya on your timeline. Because we knew something about evolution and the ancestors of whales, we were able to predict when certain body types would be found in the fossil record! Whales give us an amazing view of 'transitional fossils', that is, we can see the steps evolution took to get from a terrestrial mammal like Pakicetus, to a fully aquatic humpback whale.

see: https://evolution.berkeley.edu/evolibrary/article/evograms_03

This type of diagram is called a 'evogram' and shows the evolutionary relationships (the tree) through time (the x-axis) with illustrations of the animals. The pink lines represent important evolutionary innovations.

 

While DNA showed us that the hippopotamus and the whale are closely related, the fossils show us how that occurred, step by step. Together they tell us the story of how evolution played out over 50 million years of Earth's history.

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