Deltatheridium, << `dehl` tuh thuh RIHD ee uhm, >> was an opossumlike mammal that lived about 80 million years ago, near the end of the Cretaceous Period. Scientists consider it an important prehistoric relative of present-day marsupials. Marsupial females bear extremely immature young, and most of them have a pouch to protect their babies. Scientists believe the female Deltatheridium had a pouch as well.
Deltatheridium grew about 6 inches (15 centimeters) long, with a head about 2 inches (5 centimeters) in length. Despite its small size, it ranked as one of the larger mammals of its time.
Deltatheridium possessed large, sharp teeth and probably ate insects, lizards, and small mammals. Fossil jaws of one Deltatheridium contained a crushed skull fragment from another mammal.
Scientists first discovered Deltatheridium fossils in the 1920’s in Mongolia. But these small fragments provided limited clues about the animal. During the 1960’s and 1990’s, scientists returned to Mongolia and unearthed a number of larger, more complete Deltatheridium fossils. These discoveries provided important information about the evolution of modern marsupials. They indicated that although most marsupial species now live in Australia and South America, the first marsupials may have evolved in Asia and then migrated to other parts of the world.
