Well preserved The new find contained the remnants of several mammals in various growth and development stages, including one in the process of losing its baby teeth. Rougier and his team believe the fossils are 80 million years old which was in the Cretaceous period, when dinosaurs were reaching their peak. The specimens are so well preserved that a jaw was found with fragments of a skull that the researchers think may be the remnants of the animal's last meal. The discovery has allowed the ancient opossum-like Deltatheridium to be classified firmly as a marsupial. It also supports the theory that the mammal group, now most common in Australia, originated in Asia.
Marsupials rear their young in pouches.
They are one of three mammalian groups. Teeth clues The Deltatheridium has been confirmed as a marsupial because of information gleaned from its teeth. One of the fossils is of a young animal which died before its adult teeth had completely emerged, revealing the sequence in which they grew. Marsupials do not replace as many teeth as other mammals. It's very specialised and that is the first clear evidence we have of this marsupial-like replacement in these very weird and ancient creatures.