Paleontologists have unveiled a new genus and three new species of small insect-eating marsupials discovered in early Miocene deposits at the Riversleigh World Heritage Site in northwest Queensland—one of Australia’s premier fossil locations. Through detailed comparative and evolutionary analyses, researchers have classified these new species within a newly identified branch of the marsupial family tree, termed Keenamorphia. This lineage may represent some of Australia’s oldest marsupials, potentially tracing back to Gondwanan origins.
Reconstruction of Phantasmodon traviloni in early Miocene rainforest of northwest Queensland. Image credit: Peter Schouten.
The three newly identified marsupial species—Phantasmodon traviloni, Phantasmodon minuferox, and Keeunidae sp.—lived approximately 18 million years ago and varied in size from a shrew to a mouse (25 to 200 grams).
These species exhibit unique dental characteristics that link them to older Australian species, including Kiuna woodvarney, Ankotarinja tirarensis, and Jarsia murgonensis. The oldest known marsupial in Australia dates back to 55-million-year-old deposits found in southern Queensland.
Together, these six species form a lineage that does not conform to any previously recognized order of Australian marsupials.
This new order, Keenamorphia, represents one of the earliest offshoots of Australidelphia, the group encompassing all Australian marsupials.
Lead author Dr. Tim Churchill, a paleontologist at the University of New South Wales, stated: “Not only is this a new order, but it may also be one of the oldest lineages of Australian marsupials.”
The Keenamorphians possibly have Gondwanan roots, potentially connecting Australia’s earliest marsupials to ancient relatives from South America when the continents were still united.
This lineage appears to have faced extinction during the Miocene, with its descendants remaining unknown.
Dr. Churchill remarked, “The evolutionary history is much more complex than a single lineage leading to all of Australia’s marsupials.”
“When Australia was part of Gondwana, it was inhabited by a diverse range of primitive marsupial lineages, likely contributing to today’s marsupials.”
“Much of that history remains concealed within the fossil record, indicating that the early chapters of marsupial evolution are still unfolding.”
For further details, refer to the recent publication in the Paleontology Journal.
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Timothy James Churchill et al. A new Metatherian order (Keenamorphia, Metatheria) from Australia and new Early Miocene species from the Riversleigh World Heritage Area in northwest Queensland. Paleontology Journal, published online June 14, 2026. doi: 10.1017/jpa.2026.10238
Source: www.sci.news