Flinders fossil unlocks secrets of first animals on Earth

Researchers from American universities and the South Australian Museum have unearthed more than a dozen specimens of the new fossil at Nilpena Ediacara National Park, as recently described in the journal Evolution & Development.

The fossil, with the genus name Quaestio for the question marked shaped ridge in its centre, is one of more than 100 multicellular organisms from the Ediacaran period – an era spanning about 635 to 538 million years ago – when the first complex, macroscopic animals emerged on Earth.

Measuring up to 8cm wide, the fossils are the preserved imprints of organisms that likely moved along what was once the seafloor but is now part of the majestic Flinders Ranges landscape.

Because no animals had yet evolved to burrow through the sediment, this seafloor was covered in a layer of microorganisms that created a slimy organic mat.

Lead author of the study, Professor Scott Evans from Florida State University, said unique trace evidence uncovered by the research team suggests that Quaestio ate this mat as it moved along.

“It really speaks to the unprecedented nature of the fossil record at Nilpena to have fossils preserved directly alongside evidence of their behaviour – in this case showing us how an animal that went extinct half a billion years ago got its food,” Professor Evans said.

The full name of the fossil is Quaestio simpsonorum in recognition of Mary Lou Simpson, who is the founder and chairwoman of the Flinders Ranges Ediacara Foundation, and her husband and fellow philanthropist Antony Simpson.

The Simpsons have been involved with efforts to conserve the fossils at Nilpena for more than 20 years and the foundation has been integral to the development of Nilpena Ediacara National Park.

University of California Professor Mary Droser, who along with staff from Harvard University was part of the team that made the discovery, said the fossil had some interesting features that made it stand out from other Ediacaran species.

“What is really exciting about this fossil is that it’s basically bilaterally symmetrical, which means its right side mirrors its left side, but then it has an asymmetrical element that forms the shape of a backwards question mark,” Professor Droser said.

“This sort of symmetry indicates a certain level of genetic complexity. Humans are bilaterally symmetrical but have a number of asymmetries, for example the location of the heart and appendix. A number of other such asymmetries are found throughout the animal kingdom - this appears to be one of the first organisms to organise itself in that way.”

Professor Droser said Nilpena, which was declared a national park in 2021, was now recognised as the richest and most diverse Ediacaran fossil site on Earth.

“It’s fitting that our new fossil is named after Mary Lou and Antony Simpson, who have worked so tirelessly and enthusiastically to help preserve these fossils through the development of Nilpena Ediacara National Park,” she said.

The park is about 510km north of Adelaide and has a diversity of more than 40 fossil species recorded in the sediments of its ancient seafloors.

It is popular with both tourists and palaeontologists from around Australia and the world, as it continues to reveal evidence about how these strange and cryptic early creatures lived and even how they reproduced.

National Parks and Wildlife Service Director of Regional Operations Stuart Paul said visitors could enjoy guided tours of Nilpena Ediacara National Park, including its world-famous fossil beds.

“Nilpena is a site of huge international significance and there really is nowhere else like it in the world,” Mr Paul said.

“As well as learning about these amazing fossils out in the park, tourists can also visit the former blacksmith’s shop where one of the fossil beds is brought to life by an impressive, interpretive display with audio visual reconstructions of what these organisms looked like and how they behaved.”

For more information on Nilpena Ediacara National Park, visit https://www.parks.sa.gov.au/parks/nilpena-ediacara-national-park

For more information on the Flinders Ranges Ediacara Foundation, visit https://ediacarafoundation.org