|
Early Mammal Ancestor Discovered
Chipmunk-sized 'Eomaia' Ate Insects, Dodged Dinosaurs
 Listen to Richard Harris' report
 See a photo gallery of the discovery.
See an expanded evolutionary timetable.
April 24, 2002 --
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 Richard Harris reports for All Things Considered.
The new species -- called Eomaia -- 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.
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.
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.
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.
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.
Reporting in the journal Nature, Luo concludes that the fossil falls into a mammalian group called eutherians, a group humans belong to.
It's impossible to say whether the creature is a direct ancestor of humans. But Luo and his colleagues chose a hopeful name for the species. Eomaia, which, derived from the Greek, means "dawn mother."
In Depth
Browse for other NPR stories about evolution.
Resources
• Visit Nature online.
• Visit the Carnegie Museum of Natural History online.
• Learn more about evolution at Canada's Miller Museum of Geology.
• Explore geologic ages at the University of California, Berkeley's Museum of Paleontology.
• Explore the NOVA online feature, "A Brief History of Life."
|
