New fossil evidence from Australia has pushed the origin of reptiles on Earth back by up to 40 million years, significantly revising the timeline of vertebrate evolution. Researchers from Flinders University, led by Professor John Long, have discovered fossilized tracks in northern Victoria's Mansfield district, indicating that clawed, reptile-like amniotes were walking on land as early as 350 million years ago – well before previous estimates.

"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 35-to-40 million years older than the previous records in the Northern Hemisphere," said Professor Long, a Strategic Professor in Palaeontology at Flinders University.

The fossil trackways, preserved in rock slabs from the Carboniferous period, likely belonged to small, stumpy, Goanna-like creatures. This discovery, published in the journal Nature, challenges the conventional understanding that crown-group amniotes – the group that includes mammals, birds, and reptiles – originated later in the Carboniferous period, around 318 million years ago.

The study, co-authored by Dr. Alice Clement from Flinders University and Professor Per Erik Ahlberg from Uppsala University, utilized advanced scanning technology to create digital models of the footprints, allowing researchers to analyze their structure in unprecedented detail. Dr. Aaron Camens, another coauthor, produced heatmaps to further interpret the animals' movements, revealing behavioral insights that skeletal fossils alone cannot provide.

"This new fossilized trackway that we examined came from the early Carboniferous period, and it was significant for us to accurately identify its age," said Professor Long, whose work on this area dates back to his PhD studies in the 1980s. "We did this by comparing the different fish faunas found in these rocks with similar species in well-dated formations around the world."

La Trobe University's Dr. Jillian Garvey, who collaborated with the Taungurung Land and Waters Council for the study, emphasized the broader implications of the find, noting, "This discovery rewrites this part of evolutionary history. 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