Flinders University Professor John Long, who co-authored the study, identified the tracks as belonging to an amniote - a clade that includes reptiles, birds, and mammals. "Once we identified this, we realised this is the oldest evidence in the world of reptile-like animals walking around on land - and it pushes their evolution back by 35-to-40 million years older than the previous records in the Northern Hemisphere," says Long, a Strategic Professor in Palaeontology at Flinders.
The discovery, published in the journal Nature, suggests that such animals originated in the ancient southern supercontinent of Gondwana, where Australia was once a central part. The fossil tracks were found in rock deposits known to date from the early Carboniferous period, which began about 359 million years ago.
Long, who has been studying fossils from this area since the 1980s, explained that the Mansfield region has long been a hotspot for ancient fish and shark fossils, but direct evidence of early land-dwelling tetrapods had remained elusive. The breakthrough came when two local fossil hunters, Craig Eury and John Eason, uncovered a slab covered in fossil trackways, including a distinctive print with a hooked claw - a hallmark of amniotes.
"It was amazing how crystal clear the trackways are on the rock slab," Long recalls. "It immediately excited us, and we sensed we were onto something big - even though we had no idea just how big it is."
The tracks have been digitally scanned for detailed analysis by Dr Alice Clement and her team at Flinders, in collaboration with experts from Uppsala University in Sweden. "We study rocks and fossils of the Carboniferous and Devonian age with specific interest to observe the very important fish-tetrapod transition," says Dr Clement, highlighting the significance of these ancient trackways in understanding the move from aquatic to terrestrial life.
Dr Aaron Camens, another coauthor, developed heatmaps to visualize the fossil footprints, providing insights into the behavior and movement of these early land-dwelling vertebrates. "A skeleton can tell us only so much about what an animal could do, but a trackway actually records its behaviour," he explains.
La Trobe University's Dr Jillian Garvey, who coordinated with the Taungurung Land and Waters Council for the study, emphasized the broader impact of the find. "This discovery rewrites this part of evolutionary history," Dr Garvey says. "It indicates there is so much that has happened in Australia and Gondwana that we are still yet to uncover."
Research Report:Earliest amniote tracks recalibrate the timeline of tetrapod evolution
Related Links
Flinders University
Explore The Early Earth at TerraDaily.com
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