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Studying How Whales Swapped Feet for Fins

By Cathy Cruise, MFA '93 on November 2, 2016

Mark Uhen

Mark Uhen

Mark D. Uhen, assistant professor in Mason’s Department of Atmospheric, Oceanic, and Earth Sciences, has long been fascinated with cetaceans (whales, dolphins, and porpoises) and how they’ve evolved throughout history. While it’s common scientific knowledge these creatures evolved from terrestrial mammals, it was recently discovered that whales evolved from artiodactyls—the “even-toed ungulates” like cows and hippos. Uhen’s new book, Cetacean Paleobiology (Wiley-Blackwell, June 2016), written with Felix G. Marx and Olivier Lambert, summarizes this new awareness.

Why has it taken so long to figure this out?

New discoveries were made in the 1990s through to today in Indo-Pakistan and in Egypt, North America, and Peru. These fleshed out the story of how whales transitioned from being fully terrestrial to being semiaquatic and then fully aquatic. People used to think whales had this slow trickle of evolution and then, boom, there were all these different kinds of whales. But really early on they were diversified. Of course, the story gets more details every day with more fossils being found.cetacean-biology

Do modern techniques, such as DNA collection or new technological scans, help?

DNA can only be preserved for hundreds of thousands of years, so it can only help us understand the interrelatedness of modern things. If you sample only that, you miss all the diversity that’s in there. Early on there was a huge disagreement about the time of the origin of whales and what they’re related to because the fossils seemed to be suggesting something different from what the DNA was saying. But with more fossil discoveries, it made more sense. Today we have 3-D printers to replicate fossil structures. Recently, we wanted to examine the theory that bigger brain size relative to body size makes you smarter, so we took fossil whale skulls and put them in a CT scanner at the Smithsonian. We found that when whales learned to echolocate, their brain size went up dramatically. It went up again at the origin of the dolphin family. Those guys are highly social, so it’s guessed they needed more processing power for those relationships. Everything we did in that study we could have done without CT scanning, but it made it much faster and easier. And scanning the objects and putting them on the web makes it much easier to share fossil data.

What are you currently working on?

I’m working on a database to include every fossil on the planet. It’s called the Paleobiology Database, and I’m part of a team that has been working on it for 15 years. The idea is to get every researcher to put their fossils in. It’s completely accessible to researchers and the public. We don’t have a plan yet to get all the data in there, but we’re building the platform to do it.


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