Discovery of Keeunamorphia in Riversleigh
Researchers in Queensland’s Riversleigh World Heritage Area have uncovered fossils that could reshape our understanding of marsupial evolution. The findings reveal a previously unknown branch of the marsupial family tree, published in the Journal of Paleontology.
The study details three new species of small, insect-eating marsupials. These creatures inhabited the lush rainforests of northern Australia around 18 million years ago. So distinct are these fossils that researchers propose a new marsupial order called Keeunamorphia.
“Not only is it a new order, but it could also be one of the most ancient lineages of Australian marsupials,” says Dr. Tim Churchill, a UNSW palaeontologist and the lead author of the study.
Evolutionary Implications
Fossil evidence suggests these animals are not closely related to any marsupials living today, complicating the established story of marsupial evolution. Their dental structures resemble much older species, indicating a distinct lineage that persisted over tens of millions of years.
Dr. Churchill notes, “Whatever these things were, they seemed to be primitive compared to other marsupials at the time.” This discovery hints at a more diverse early marsupial fauna in Australia than previously thought.
Scientists generally believe Australia’s marsupials descended from a common ancestor that arrived from South America via Antarctica over 50 million years ago. However, the new fossils complicate this narrative by suggesting these marsupials belonged to a distinct lineage.
When Australia was part of Gondwana, it likely hosted various primitive marsupial lineages. Several of these lineages may have contributed to the marsupials we see today, indicating a complex evolutionary history.
The researchers explain that much of this history remains hidden in gaps in the fossil record. the earliest chapters of marsupial evolution are still being written.
For further information, Dr. Tim Churchill can be contacted through UNSW Science at 0432 912 060.
