635-million-year-old: Question mark-shaped ocean-dwelling animal found

Researchers discovered Quaestio, a new fossil at Nilpena Ediacara National Park, 635 to 538 million years old. It provides new insights into the first form of animal life on Earth.

At Nilpena Ediacara National Park in Australia, famous for fossils of early animal life, researchers dubbed the brand new, though ancient animal Quaestio for the question mark on its flat, fleshy body.

About 8cm wide, Quaestio is one of the first animals to evolve. Dating back to the Ediacaran period, over 500 million years ago, it’s one of “the first complex, macroscopic animals” that emerged on Earth.

At the time, animals hadn’t yet developed the capacity to burrow. They were just coming into being, so the ocean was covered in a “slimy mat of microorganisms.” Researchers believe that Quaestio might have moved along the ocean floor to feed.

Professor Scott Evans from Florida State University, lead author of a recent study, said, “It really speaks to the unprecedented nature of the fossil record at Nilpena to have fossils preserved directly alongside evidence of their behavior—in this case, showing us how an animal that went extinct half a billion years ago got its food.”

Quaestio simpsonorum : brand new but very old

Quaestio simpsonorum had been hiding in plain sight at Nilpena Ediacara National Park, described as a “living chronicle of Earth’s earliest complex animal life.”

It was a significant discovery that it was named after Mary Lou Simpson, the founder, and chairwoman of the Flinders Ranges Ediacara Foundation, and her husband, who has supported the organization’s efforts to find and preserve animals such as Quaestio .

This round creature can now claim its rightful place among the approximately 100 multicellular organisms from the Ediacaran period. However, researchers even found remarkable features that distinguished Quaestio from other lifeforms.

“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 backward question mark,” Professor Droser said in an official statement.

“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.”

Head north 510km of Adelaide to see Quaestio

Visitors can travel about 510 km north of Adelaide and witness a new animal among the 40 fossil species from this definitive moment in time that the park holds, which was once underwater. Its fossil beds are famous.

“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.”

The study has just been published in Evolution and Development.