A life reconstruction of Ambondro mahabo, the four-inch-long tribosphenic mammal.Credit...Flynn & Wyss, Scientific American, 2004
The New York Times has an article about an unexpected discovery. In 1996, paleontologists found mammal bones in an unexpected place.... northwestern Madagascar. A tiny 167 million year old jaw fragment from an animal that was out of place by 25 million years. The fossil belonged to Ambondro mahabo, a small creature that opened the door to the conclusion that modern mammals originated in the Southern Hemisphere.
“The prevailing wisdom suggested that we shouldn’t find something like that from the time interval we were sampling, nor from the Southern Hemisphere,” said John Flynn, the paleontologist who led that dig and is now the Frick curator of fossil mammals at the American Museum of Natural History in New York.
It takes more than a single fossil to overturn an entire theory of evolution. But a review of existing fossil holdings published last year in the journal Alcheringa sought to turn decades of paleontological wisdom on its head. After an exhaustive study of skulls, jaws and teeth, a team of Australian paleontologists presented their conclusion that modern mammals originated in the Southern Hemisphere.
Their findings have set off an impassioned debate, revealing a North-South divide. Defenders of the Northern Hemisphere hypothesis highlight weaknesses they see in the latest findings. In response, supporters of the Southern Hemisphere origin, like Dr. Flynn, say it is time for paleontologists to grapple with the argument that their field’s understanding of natural history may be slanted toward the half of the world where scientists have carried out the most digs.
