Rodhocetus

The Department of Geology

The School of Earth, Society, and Environment

College of Liberal Arts and Sciences

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Correct! The DNA evidence supported the Molecular Biologist hypothesis. But paleontologists weren't done asking questions. Open the packet labeled '4' and check the contents. You should have A Rodhocetus fossil A Cow ankle bone A Pachyaena ankle bone A Rodhocetus ankle bone Because Mesonychids are extinct there is no DNA to test against whale DNA, so DNA can't conclusively tell us if whales are more closely related to Artiodactyls or Mesonychids. We need some sort of fossil evidence to solve this problem. All Artiodactyls have a particular type of ankle bone called a 'double pulley'. It looks like this:

The 'double-pulley' ankle bone of a deer, a kind of Artiodactyl

No other animals have ankle bones that look like this. Philip Gingrich realized that: A) if whales were more closely related to Artiodactyls, they should have this type of bone on their ancient hind legs or B) if whales were more closely related to Mesonychids, they should NOT have this type of bone on their ancient hind legs This set up an evolutionary prediction that could be TESTED by finding the correct fossils. He went to Pakistan and eventually found Rodhocetus in rocks that were about 46 million years old. Place the Rodhocetus strip at 46 mya on your timeline. Importantly, Rodhocetus was much older than Dorudon and had working hind limbs. Examine the ankle bones of Rodhocetus, Pachyaena, and the Cow. Remember that Pachyaena is a Mesonycid and the Cow is an Artiodactyl

Is the Rodhocetus ankle bone more similar to the Pachyaena or Cow ankle bones? Click Here to Answer

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