What’s happening?
A new fossil discovery in Murgon, on the traditional lands of the Waka Waka people in south-eastern Queensland, has unveiled Australia’s oldest known species of tree frog.
Named Litoria tylerantiqua, this ancient frog pushes back the evolutionary timeline of Australian tree frogs by over 20 million years.
The finding, published in the Journal of Vertebrate Palaeontology, redefines scientific understanding of when Australian and South American tree frogs diverged.
The species is named in honour of the late Michael Tyler, an iconic Australian herpetologist known globally for his work on frogs and toads.
Dr Roy Farman, lead author and adjunct associate lecturer at UNSW School of Biological, Earth & Environmental Sciences, says, “It is only fitting to name Australia’s earliest tree frog in honour of a man who was a giant in Australian frog research and in particular the first to explore the fossil record for Australian frogs.”
Why it matters
This groundbreaking discovery reveals that Australian tree frogs separated from their South American relatives much earlier than previously believed.
Earlier estimates based on genetic data placed the divergence at 33 million years ago. However, the fossil of Litoria tylerantiqua, dated to around 55 million years ago, suggests the evolutionary split happened significantly earlier.
Dr Farman explains, “Our research indicates that that date is at least 22 million years too young. While molecular studies are important for understanding the evolutionary relationships of different groups of animals, these studies should be calibrated using knowledge from the fossil record and in this case the fossil record provides a more accurate time for separation of the southern world’s tree frogs.”
Local Impact
The fossil find at Murgon not only honours Australia’s palaeontological legacy but also highlights the scientific significance of regional fossil sites.
This discovery strengthens the case for further investment in fossil research and conservation across Queensland, particularly in areas like Rockhampton and surrounding regions where ancient environments may still yield more secrets.
By the numbers
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Litoria tylerantiqua dates back 55 million years, making it the oldest known pelodryadid tree frog in Australia.
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The discovery extends the fossil record of Australian tree frogs by 30 million years.
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The previous estimated divergence date between Australian and South American tree frogs was 33 million years ago.
Zoom In
Researchers used advanced techniques to examine the fossils, including three-dimensional geometric morphometrics.
They CT scanned spirit-preserved frogs from museum collections to generate 3D models of skeletal structures that were otherwise hidden. This method had only been used once before on fossil frogs.
Dr Farman said, “We had a real problem at the start of this study because the pelvic bones of most living frogs were invisible inside whole pickled frogs rather than available for study as skeletons. Museums understandably want to ensure these often unique or rare pickled specimens remain intact for molecular studies because DNA can be obtained from their soft tissues. This meant that instead of skeletonising these specimens, we needed instead to make CT scans of them, enabling us to create 3D models of their otherwise invisible skeletons.”
By comparing the fossil ilia — one of the three pelvic bones — with those of modern frogs, researchers concluded that Litoria tylerantiqua is more closely related to Australian tree frogs (pelodryadids) than South American phyllomedusids.
Zoom Out
Australia, South America and Antarctica were connected 55 million years ago as part of the last remnants of Gondwana.
Warmer climates and a continuous forest corridor linked the continents, allowing animals like tree frogs to spread across the landmass. This discovery adds crucial data to our understanding of how species dispersed across ancient continents.
Previously, the earliest evidence of Australian tree frogs came from the Late Oligocene (26 million years ago) and Early Miocene (23 million years ago).
Fossils were found at Kangaroo Well in the Northern Territory, Etadunna Formation at Lake Palankarinna in South Australia, and Riversleigh in Queensland. The Murgon fossil now predates these by tens of millions of years.
What to look for next?
Litoria tylerantiqua joins Platyplectrum casca (previously Lechriodus casca) as one of only two known frog fossils from Murgon. Both species have living relatives in Australia and New Guinea, showing extraordinary resilience.
Dr Farman emphasises the relevance of the fossil record to modern conservation efforts: “Despite their delicate nature, frogs have been surprisingly successful at surviving several mass extinction events since their origins about 250 million years ago, including the mass extinction 66 million years ago that took out the non-flying dinosaurs.”
He warns that current threats, including rapid climate change and chytrid fungus, may be among the worst frogs have faced. “The fossil record could reveal how some frog groups overcame previous challenges, perhaps by adapting to new, less-threatening habitats. This could provide clues about how we might be able to help by translocating some threatened frogs into more future-secure habitats.”
For example, frogs like the endangered southern corroboree frog may have better survival chances if reintroduced into historically suitable environments.
