Ancient creature discovered in Australia shakes up our understanding of evolution

© Photoholgic/Unsplash

An international team of researchers unearthed the fossil of a 575-million-year-old sea creature named Quaestio simpsonorum, which may well be l’ ;#8217;one of the oldest complex animals known to date. This exceptional find suggests that the complexification of organisms occurred earlier than previously thought.

In the theory of evolution, the complexification of organisms refers to the evolutionary process by which living beings have passed from simple forms to increasingly complex forms, with ever more elaborate biological structures and functions. As if life had passed from a single thread of wool to an intricate tapestry, with each thread contributing to a harmonious pattern

A strange fossil with unique features

The Quaestio simpsonorum, whose name evokes its enigmatic shape, appears as a flattened disk slightly smaller than a human palm. Its most striking feature is a question mark-shaped structure located at one end. This unique feature not only inspired its name, but also reveals a previously unsuspected anatomical complexity for an organism from this era.

Dr. Scott Evans, a geologist at Florida State University and co-author of the study, emphasizes the weight of this discovery in the field of paleozoology. ” No other fossil from this period has revealed such an obvious organization ». This fossil therefore reveals a degree of clarity in its structure that had never been observed before, at least for a fossil dating from the Ediacaran (geological period extending from -635 to -541 million years ago).

Indeed, the Quaestio presents a bilateral symmetry, clearly distinguishing a left side and a right side. This is a very common characteristic in current animals, from the human species to insects. This bilateral symmetry is often associated with increased mobility and organ specialization. It also exhibits asymmetrical torsion, which indicates that one part of the Quaestio body has rotated relative to another part, creating this asymmetry. This is not random: it is probably related to a specific function, such as locomotion or feeding.

This combination of these two features suggests that the Quaestio was a much more complex organism than many of its Ediacaran contemporaries. It had never been observed so early in evolutionary history.

Artist's vision of the Quaestio simpsonorum, with the famous point d& #8217;questioning its external structure. © Walker Weyland

The first steps of animal mobility

Beyond its intriguing morphology, the Quaestio simpsonorum provides tangible evidence of mobility,a fundamental capacity in animal evolution. The researchers discovered not only several fossilized specimens of the organism, but also trace fossils in the form of imprints left by their bodies in the now-petrified mat of algae and microscopic bacteria.

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Dr. Ian Hughes, an evolutionary biologist at Harvard University,excitedly describes the moment one of the fossils was discovered: “One of the most exciting moments was when we turned over a rock, brushed it, and saw what was clearly a trace fossil behind a specimen of Quaestio – a clear sign that the organism was mobile, that it could move ».

These tracks, with slightly offset contours compared to the harder edges of the animal's footprint, constitute irrefutable proof that these creatures were among the first animals capable of moving on their own.

The biological big bang: the 575 million years that changed everything

The discovery of the Quaestio simpsonorum is part of a broader research context concerning the origins of complex life forms on Earth. These fossils belong to a group of organisms known as the Ediacara, which marks the transition from a world dominated by single-celled organisms to the Cambrian explosion of diversity.(-541 to -485 million years ago). This is when a multitude of new species appeared, with complex and diverse structures: arthropods, trilobites and the first vertebrates.

Professor Mary Droser is a paleontologist and chief scientist at Nilpena Ediacara National Park where the fossil was discovered. For her, this type of research and discovery is essential to advance our understanding of animal evolution. “ Studying the history of life through fossils tells us about how animals evolve and the processes that cause them to go extinct, whether it's climate change or low oxygen levels ” she explains.

Fossils are time capsules that allow us to go back in time and observe life forms that existed millions of years ago. By studying these remains, paleontologists can reconstruct the appearance, lifestyle, and evolutionary relationships of past organisms. Another very important point: by studying past events, such as mass extinctions linked to climate change, scientists can better anticipate the consequences of current global warming on biodiversity.

The Nilpena Ediacara National Park, which is home to the oldest known animal fossils on Earth, is currently waiting to be listed as a UNESCO World Heritage Site. This recognition would thus help protect these precious testimonies of the living history of our planet and deepen our understanding of the complex mechanisms that have shaped life as we know it today. Of course, we always have our eyes fixed on the sky in anticipation of a possible sign of extraterrestrial life forms, but we must not forget that our planet still holds many mysteries. Quaestio simpsonorum is proof of this, even if it is not, in appearance, so spectacular.

• Researchers have discovered Quaestio simpsonorum, a 575-million-year-old fossil that is likely one of the oldest known complex animals.
• This fossil exhibits bilateral symmetry and evidence of mobility, suggesting that organisms began to become more complex earlier than previously thought.
• Discovered in Nilpena Ediacara National Park, this fossil offers valuable clues about animal evolution and could help us better understand the processes of extinction and climate change.

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