Fossil Discovery in Australia Pushes Timeline of Animal Evolution Back by 40 Million Years

A newly uncovered set of fossilized tracks in Australia has dramatically altered the scientific understanding of animal evolution, pushing the emergence of reptile-like animals back by as much as 40 million years. This discovery, detailed in a recent study published in the journal Nature, provides the oldest known evidence of amniotes—creatures that include reptiles, birds, and mammals—walking on land during the Carboniferous period, approximately 350 million years ago.

The fossilized tracks were found in the Mansfield district of northern Victoria, within the Snowy Plains Formation on Taungurung Country. The tracks are attributed to a small, clawed-footed animal resembling a primitive sauropsid, a group that includes modern reptiles. According to lead researcher Professor John Long of Flinders University, these tracks represent the earliest evidence of reptile-like animals traversing terrestrial environments, predating previous records from the Northern Hemisphere by 35 to 40 million years.

This breakthrough challenges long-standing assumptions about the timeline and geography of tetrapod evolution. Amniotes are distinguished by their ability to lay eggs on land, thanks to the development of the amnion—a protective membrane around the embryo—freeing them from the need for aquatic reproduction, unlike amphibians. The presence of such advanced traits in these ancient tracks suggests that the evolutionary leap to land-based reproduction and mobility occurred much earlier than previously believed.

The discovery also supports broader theories about the rapid and dynamic nature of early animal evolution. Recent studies on ancient trace fossils and genome evolution in other animal groups, such as annelids and insects, further highlight the complexity and variability of evolutionary processes during this formative period in Earth’s history.

Paleontologists emphasize that these findings not only rewrite the timeline of reptile evolution but also provide critical insights into the origins of the major animal groups that dominate terrestrial ecosystems today.