Eomaia, the "dawn mother"

Carnegie, Jul/Aug 2002

Carnegie Scientists discover the first placental mammal

Scoring another first in the field of vertebrate paleontology, Carnegie scientists have just published their findings on the world's first placental mammal, called "Eomaia," the "dawn mother." This small fossil specimen, some 125 million years old, is the ancestor of all the placental species that bear their young live. What followed them has ranged from elephants to manatees, tree sloths, armadillos, hedgehogs, bats, pangolins, horses, rhinos, cows, pigs, whales, monkeys, and of course humans, and man's best friends--dogs.

Eomaia resembled a large shrew, and was an active climber. It had claws and feet which gave it considerable ability to walk on branches and in the trees. It was an insectivore. The fossil was discovered in 2000 at a field site in northeastern China, but Carnegie Museum of Natural History paleontologist Zhexi Luo, and mammalogy curator John Wible, were in a good position with their colleagues to bring it to light to the world's scientific community. Their article was published in the prestigious British scientific journal Nature (April 25, 2002).

"This is a very important find," says Zhexi Luo, who worked with colleagues he calls "the best in China," from the Chinese Academy of Geological Science. This is the earliest species in placental mammal evolution that has a climbing adaptation, and shows how early diversification of species began. The specimen is older by ten million years than the next oldest placentals known only by three isolated teeth, and older by 40 million years than the next oldest placentals represented by skulls. It helps to fill fresh information in a previously blank period of the placental mammal history.