Researchers reveal ancient origins of modern opossum   PhysOrg - December 16, 2009

A University of Florida researcher has co-authored a study tracing the evolution of the modern opossum back to the extinction of the dinosaurs and finding evidence to support North America as the center of origin for all living marsupials.

In parts of North America today, opossums are one of the most commonly observed mammals around," Bloch said. "This fossil skull shows its roots going back to the extinction of the dinosaurs. This is literally the fossil that shows us the ancestry of that animal.

The study's examination of the two skeletons gives a first glimpse into the form and structure of primitive marsupials and shows that they were more terrestrial than modern opossums. The skeletons came from the late Oligocene and were found in the White River Badlands of Wyoming.