LONDON, Dec. 11 (UPI) -- The oldest known fossil skeleton of an ancestor of modern marsupials has been unearthed in northeastern China.
New Scientist magazine said the fossil is 50 million years older than the previous record holder, helping fill a key gap in the understanding of early mammal evolution.
China's 125 million years old Yixian rock formation has produced a spectacular collection of early mammal fossils, including, in 2002, the earliest known placental mammal, Eomaia scansoria.
The most recent discovery is a mouse-sized ancestor of opossums and kangaroos, Sinodelphys szalayi.
The discovery of both the oldest known marsupial and placental mammal at the same site gives a powerful boost to a theory that the two important lineages evolved in Eurasia, and then spread to the rest of the world.
