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It's a 125-million-year-old mouse-sized creature with a dense pelt and long fingers. 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src="https://web.archive.org/web/20020815052228js_/http://www.npr.org/include/javascript/emailafriend_top.js"></script> <p class="pagetitle">Early Mammal Ancestor Discovered<br> <span class="subtitle"> Chipmunk-sized 'Eomaia' Ate Insects, Dodged Dinosaurs</span></p>  <p class="text"> <a href="https://web.archive.org/web/20020815052228/http://www.npr.org/ramfiles/atc/20020424.atc.12.ram"><img src="https://web.archive.org/web/20020815052228im_/http://www.npr.org/images/audiospeakericon.gif" border="0" align="left" width="18" height="18" alt="audio icon"></a><a href="https://web.archive.org/web/20020815052228/http://www.npr.org/ramfiles/atc/20020424.atc.12.ram">Listen to Richard Harris' report</a> </p> <a class="text" href="javascript:void(0);" onclick="popUp('/programs/atc/features/2002/apr/mammals/photo1.html','width=610,height=425,toolbars=no,resizeable=yes');"><img src="/web/20020815052228im_/http://www.npr.org/images/icon_more.gif" border="0" alt="photo gallery" align="left"> See a photo gallery of the discovery.</a><br><br> <a class="text" href="/web/20020815052228/http://www.npr.org/programs/atc/features/2002/apr/mammals/timeline.html"><img src="/web/20020815052228im_/http://www.npr.org/images/icon_more.gif" border="0" alt="photo gallery" align="left"> See an expanded evolutionary timetable.</a><br><br> <table align="left" width="140" cellpadding="0" cellspacing="10" border="0"> <tr valign="top"> <td><img src="/web/20020815052228im_/http://www.npr.org/programs/atc/features/2002/apr/mammals/eomaia.jpg" width="140" height="198" border="1" alt="Eomaia scansoria"><br><span class="caption">Fossil of <i>Eomaia scansoria</i><br><i>Photo: Ji et al. Ms. for <i>Nature</i></span></td> </tr> <tr valign="top"> <td><img src="https://web.archive.org/web/20020815052228im_/http://www.npr.org/images/spacer_gray.gif" width="140" height="1"><p class="caption"> <b>Evolutionary Highlights</b><br><br> 3.5 billion years ago: Single-celled microbes <br><br> 1.8 bya: Single-celled microbes with nuclei<br><br> 650 mya: Soft-bodied multi-celled animals<br><br> 500 mya: Marine vertebrates <br><br> 435 mya: Land plants and animals<br><br> 245 mya: Dinosaurs<br><br> 200 mya: Mammals<br><br> <b>125 mya: <i>Eomaia</i>, placental mammals</b><br><br> 55 mya: Primates<br><br> 4 mya: Hominids<br><br> 2.3 mya: The rise of the <i>Homo</i> species<br><br> 200,000 ya: Modern humans, <i>Homo Sapiens</i><br><br> <i><a class="caption" href="/web/20020815052228/http://www.npr.org/programs/atc/features/2002/apr/mammals/timeline.html">See an expanded evolutionary timetable.</a></i> </p> <img src="https://web.archive.org/web/20020815052228im_/http://www.npr.org/images/spacer_gray.gif" width="140" height="1"></td> </tr> </table> <p class="text"> <b>April 24, 2002</b> -- Scientists today announced the discovery of a spectacular fossil: a mammal that lived alongside dinosaurs 125 million years ago. This new species, reminiscent of a chipmunk, is the earliest known ancestor of placental mammals, a group that includes humans. Its remarkably well-preserved remains provide clues about the evolution of man's kin. NPR's <a href="https://web.archive.org/web/20020815052228/http://www.npr.org/about/people/bios/rharris.html">Richard Harris</a> reports for <i>All Things Considered</i>. <br><br> The new species -- called <i>Eomaia</i> -- turned up two years ago, when amateur fossil hunters digging in a quarry in China unearthed a chunk of rock containing tiny fossilized bones. They brought their find to scientists who had been exploring the area, looking for their own fossils.<br><br> It was a rare full skeleton of an ancient mammal, about 5 inches long. Dr. Zhe-Xi Luo, a curator at the Carnegie Museum of Natural History in Pittsburgh, Pa., was ecstatic to discover that the rock preserving the fossil also recorded impressions of soft tissue, and even hair. Most fossil finds involve only a few bones, and fossilized hair is rarely seen.<br><br> Eomaia was adapted to scramble through bushes and trees -- presumably to find food, but also to get away from predators, which could well have included small dinosaurs. <br><br> Scientists have previously unearthed feathered dinosaurs in the same Chinese rock formation, called Yixian, along with other early mammals, plants and insects. Anne Weil, a Duke University paleontologist, says that's what has drawn researchers to the site.<br><br> Taken together, the fossils recreate a vivid prehistoric scene that shows incredible diversity -- especially among mammals. But most of those mammal lineages have since died out. <br><br> Reporting in the journal <i>Nature</i>, Luo concludes that the fossil falls into a mammalian group called eutherians, a group humans belong to. <br><br> It's impossible to say whether the creature is a direct ancestor of humans. 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