Kennesaw State University Magazine Summer 2011 KSU Magazine : Page 28

Biology professor Marcus Davis spends summers in the Canadian Arctic searching for fossils like this saber-toothed cat skull. Linking BY ROBERT S. GODLEWSKI E volutionary biologist Marcus C. Davis delves into the past with an eye on the future, knowing that his research will shed new light on birth defects and limb regeneration in humans. An assistant professor of biology in KSU’s College of Science and Mathematics, Davis spends summers digging for fossils in the Canadian Arctic where temperatures hover around freezing and the sun never sets. Davis was among a group of researchers led by the University of Chicago’s Neil Shubin, that made a key discovery while exploring 375 million-year-old fossilized streambeds 600 miles from the North Pole — the skeletons of well-preserved fossil fish. They were searching for what Davis describes as a transitional organism between fish and land-living vertebrates, which possessed attributes of both fish and amphibians. “What we found was a mosaic animal with long and muscular limbs like an amphibian, with a fish-like fin at the end for swimming,” he said. “Unlike fish, it had a distinctive neck — a key attribute that allows land animals to move their head independently from their body.” The team named the “missing link” fossil Tiktaalik (pronounced tic-TAH’-lic) roseae , and nicknamed it the “fishapod,” or fish with feet. The New York Times quoted H. Richard Lane, director of paleobiology at the National Science Foundation, as saying, “These exciting discoveries are providing fossil Rosetta Stones 28 Kennesaw State University Magazine | SUMMER 2011

Linking The Past

Robert S. Godlewski

Evolutionary biologist Marcus C. Davis delves into the past with an eye on the future, knowing that his research will shed new light on birth defects and limb regeneration in humans.<br /> <br /> An assistant professor of biology in KSU’s College of Science and Mathematics, Davis spends summers digging for fossils in the Canadian Arctic where temperatures hover around freezing and the sun never sets.<br /> <br /> Davis was among a group of researchers led by the University of Chicago’s Neil Shubin, that made a key discovery while exploring 375 million-year-old fossilized streambeds 600 miles from the North Pole — the skeletons of well-preserved fossil fish.<br /> <br /> They were searching for what Davis describes as a transitional organism between fish and land-living vertebrates, which possessed attributes of both fish and amphibians.<br /> <br /> “What we found was a mosaic animal with long and muscular limbs like an amphibian, with a fish-like fin at the end for swimming,” he said. “Unlike fish, it had a distinctive neck — a key attribute that allows land animals to move their head independently from their body.”<br /> <br /> The team named the “missing link” fossil Tiktaalik (pronounced tic-TAH’-lic) roseae, and nicknamed it the “fishapod,” or fish with feet.<br /> <br /> The New York Times quoted H. Richard Lane, director of paleobiology at the National Science Foundation, as saying, “These exciting discoveries are providing fossil Rosetta Stones for a deeper undSo, besides the evolutionary insights, these discoveries may lead to medical breakthroughs since many fish and amphibians can replace damaged or lost limbs.erstanding of this evolutionary milestone — the link from fish to land-roaming tetrapods.”<br /> <br /> Davis said his current research explores the mechanisms of evolutionary change that underlie the origins of new animal body plans. “I integrate information from the fossil record with the investigation of developmental mechanisms in living vertebrates. I’m trying to determine whether fish have fingers, or something that became fingers in all of us ‘land fish.’”<br /> <br /> The patterns of limb evolution across hundreds of millions of years have allowed researchers like Davis to develop hypotheses about how limbs form and which genes are involved.<br /> <br /> So, besides the evolutionary insights, these discoveries may lead to medical breakthroughs since many fish and amphibians can replace damaged or lost limbs.<br /> <br /> Since these vertebrates and mammals, including humans, use mostly the same genes to build their limbs, researchers are confident it will one day be possible to regenerate lost digits and limbs in humans.<br /> <br /> “Insights from our study also have allowed us to clarify the very confusing observations that have been made regarding birth defects in humans. Which is why, in polydactylism, one of the most common forms of birth defects, there are extra digits – six, seven or eight but never more than eight digits,” Davis said.<br /> <br /> Davis made a return trip to the Arctic this summer. “It is now time to open the next chapter in exploration and I have been invited back to play a role,” he said. “We are excited to explore some new exposures, on new islands, that we did not explore over the last decade.”

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