Paleontologists have discovered fossilized tracks of a reptile-like animal — securely dated to the early Tournaisian age of the Carboniferous period, about 355 million years ago — in the Snowy Plains Formation of Victoria in Australia. This discovery indicates that such animals originated in the southern supercontinent Gondwana, of which Australia was a central part.
An artist’s impression of what the early reptile trackmaker would look like from 355 million years ago. Image credit: Martin Ambrozik.
Tetrapods evolved from a group of fish that left the sea about 390 million years ago, during the Devonian period.
They became the ancestors of all modern backboned land animals, i.e. amphibians and amniotes, a group that includes mammals, reptiles and birds.
The oldest amniote fossils previously found come from the later part of the Carboniferous period and are about 320 million years old.
Discovered by two amateur paleontologists, the 355-million-year-old track-bearing slab from the Snowy Plains Formation shows that reptiles already existed 35 million years earlier, at the beginning of the Carboniferous.
“Once we identified this, we realized this is the oldest evidence in the world of reptile-like animals walking around on land — and it pushes their evolution back by at least 35 million years older than the previous records in the northern hemisphere,” said Flinders University Professor John Long.
“The fossil tracks, discovered in the Mansfield district of northern Victoria in Australia, were made by an animal that would have looked like a small, stumpy, goanna-like creature.”
The 355-million-year-old track-bearing slab from the Snowy Plains Formation, Australia. Image credit: Long et al., doi: 10.1038/s41586-025-08884-5.
“When I saw this specimen for the first time, I was very surprised, after just a few seconds I noticed that there were clearly preserved claw marks,” said Dr. Grzegorz Niedźwiedzki, a researcher at Uppsala University.
“Claws are present in all early amniotes, but almost never in other groups of tetrapods,” added Uppsala University Professor Per Erik Ahlberg.
“The combination of the claw scratches and the shape of the feet suggests that the trackmaker was a primitive reptile.”
According to the team, the implications of this discovery for the early evolution of tetrapods are profound.
All stem-tetrapod and stem-amniote lineages must have originated during the Devonian period — but tetrapod evolution proceeded much faster, and the Devonian tetrapod record is much less complete than we have believed.
“A skeleton can tell us only so much about what an animal could do, but a trackway actually records its behavior and tells us how this animal was moving,” said Flinders University’s Dr. Alice Clement.
“This new fossilized trackway that we examined came from the early Carboniferous period, and it was significant for us to accurately identify its age — so we did this by comparing the different fish faunas that appear in these rocks with the same species and similar forms that occur in well-dated rocks from around the world, and that gave us a time constraint of about 10 million years.”
“This discovery rewrites this part of evolutionary history,” said La Trobe University’s Dr. Jillian Garvey.
“It indicates there is so much that has happened in Australia and Gondwana that we are still yet to uncover.”
The discovery is described in a paper published in the journal Nature.
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J.A. Long et al. Earliest amniote tracks recalibrate the timeline of tetrapod evolution. Nature, published online May 14, 2025; doi: 10.1038/s41586-025-08884-5
