Paleontologists have recently identified a new genus and three new species of small insect-eating marsupials from early Miocene deposits at the Riversleigh World Heritage Site in Northwest Queensland, one of Australia’s most prolific fossil sites. Comparative and evolutionary analyses suggest that these new species are part of a newly recognized branch in the marsupial family tree, termed Keenamorphia. This lineage may represent some of Australia’s earliest marsupials, potentially tracing its origins back to Gondwana.
Reconstruction of Phantasmodon traviloni in the early Miocene rainforest of Northwest Queensland. Image credit: Peter Schouten.
The three newly identified marsupial species, Phantasmodon traviloni, Phantasmodon minuferox, and Keenamorphia sp., lived around 18 million years ago, with sizes ranging from shrews to mice (25 to 200 grams).
These species exhibit unique dental characteristics that align them with older Australian species such as Kiuna woodvarney, Ankotarinja tirarensis, and Jarsia murgonensis. The oldest known marsupial from the continent was discovered in 55-million-year-old deposits in southern Queensland.
Collectively, these six species form a lineage that does not fit into any previously recognized order of Australian marsupials.
This new order, called Keenamorphia, represents one of the earliest offshoots of Australidelphia, encompassing all Australian marsupials.
“This discovery not only establishes a new order but may also reveal one of the oldest lineages of Australian marsupials,” stated lead author Dr. Tim Churchill, a paleontologist at the University of New South Wales.
Keenamorphians are thought to have Gondwanan origins, potentially linking the earliest marsupials of Australia with ancient relatives from South America when the two continents were still connected.
This lineage appears to have disappeared during the Miocene, with no known descendants currently.
“The evolutionary history of marsupials is far more intricate than a linear progression leading to all extant Australian marsupials,” Dr. Churchill explained.
“When Australia was part of Gondwana, it was home to a variety of primitive marsupial lineages, and it is probable that some of these contributed to modern species.”
“Much of this history remains obscured in the fossil record, indicating that the early chapters of marsupial evolution are still unfolding.”
For further details, refer to the recent study published in the Paleontology Journal this month.
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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
