It’s been a record breaking month of fossil discoveries for scientists in the Victorian Alps. This intriguing discovery has extended the timeline of reptilian evolution by a remarkable 40 million years! Led by John Long, a palaeontologist at Flinders University, this breakthrough involves a slab of rock containing 18 distinct footprints, believed to belong to the earliest-known amniote, an ancestor of most land-based creatures. Craig Eury and John Eason with the beautifully preserved late Cretaceous Dinosaur fossil they discovered while fossil hunting around Mansfield. What a remarkable piece of history to hold — this fossil is about 356 million years old!
The find first came about while working on the bank of the Broken River, where the team members made the chance encounter with a textbook-sized sandstone block. The footprints show close resemblance to the anatomy of modern iguana feet, suggesting an evolutionary bridge far closer. The study authors think that these clawed imprints are the best evidence that this creature was terrestrial. Amphibians in general are not known for such adaptations, hinting that this remarkable animal is unique.
The Significance of the Discovery
The fossil’s implications for our understanding of vertebrate evolution are enormous. John Long emphasized that the find is “of immense importance to our understanding of when and where the main vertebrate group evolved.” These fossilized footprints hold key information about an evolutionary transition—the move of life from the sea to land. This transition leads to one of the most significant transitions in Earth’s history.
Anne Warren, a Texas A&M paleontologist who helped lead the study, said that the presence of clawed digits in the theropod tracks makes them particularly unique. This new track indisputably belongs to an amniote. It possesses five clawed digits on the front foot. In embryos of the adult amniotes, there are four anterior digits with no claws in amphibians. This key difference represents a significant evolutionary chasm, further bolstering the idea that this animal belongs to the very base of reptilian evolution.
The trackway is made up of two parallel prints moving in the same direction. One slab has a clear set of paw prints and another has more faint impressions of claws. The researchers suggest the same animal made both types of footprints as it moved through its habitat. They think those nice, clearly-defined footprints went down first.
A Connection to Local History
John Long’s connection to Mansfield runs deep. He has been especially intentional about connecting with his local community, speaking to audiences at the Mansfield public library. During these sessions, he imparts wonderful knowledge of the region’s abundant fossil treasure. Long expressed his delight at this recent discovery, stating, “You’ve got this big, vast area of red carboniferous rocks in the basin there in Mansfield and you can still find world-class fossils there.”
Craig Eury, one of those amateur fossil hunters, recalled the thrilling day he first found the footprints. The thrill of that find continues to bring him joy to this day. “It was literally the footprints that caught my eye — the light hit the rock in a way that cast a shadow on the footprints,” he said. Eury’s passion for paleontology shines through his words as he acknowledged his lack of formal education in science: It’s just a fantastic thing to be able to look forward and contribute to, because I left school at 15… I don’t have formal education in any technological area or scientific area.
John Eason, another fossil hunter on the team that made the discovery, shared Eury’s sense of wonder. “I couldn’t believe it — it’s rare in life you find what you’ve always been dreaming about finding,” he remarked.
Analyzing the Footprints
In this new study, we explore the implications of these footprints well beyond their original discovery. Anthony Romilio, a fellow colleague to Long, explained that tracks like this are usually linked to creatures that have the kind of life structure that water can sustain. He posed an interesting analogy: “Perhaps this animal was not walking, supporting its own weight … It’s analogous to swimming.”
Long provided further clarification on this matter, asserting that “the sharp claws digging in the second trackway are too precise to suggest they were digging or clawing the sediment underwater.” This claim is consistent with their results that provide definitive evidence for the creature’s adaptation to life on land.
This detailed study of these footprints restores depth to our knowledge of early amniotes. It poses fascinating questions as to their behavior and interactions with the environment during that time period. The remarkable fossil gives a glimpse of a period when terrestrial animals started to evolve from their watery ancestry.
