Fossils preserved a snapshot of life before the Cambrian explosionAn image of Spriggina flounensi fossil.
Located in South Australia’s Flinders Ranges, Nilpena preserves one of the world’s richest fossil records from the Ediacaran Period, roughly 635-538 million years ago.
This consistent pattern suggests that Spriggina was not randomly curved by fossilisation but instead showed a directional preference during life.
Researchers believe that this symmetry created opportunities for specialised movement, sensory processing, and behavioural preferences that eventually became widespread across the animal kingdom.
However, the discoveries of these preserved fossils from South Australia suggest that some species possessed complex body organisation, directional movement and potentially advanced sensory capabilities.
An image of Spriggina flounensi. Image credits: Wikimedia Commons
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Fossils preserved a snapshot of life before the Cambrian explosion
An image of Spriggina flounensi fossil. Image credits: Wikimedia Commons
Bilateral symmetry may have paved the way for handedness
Scientists believe the evolutionary origins of handedness may extend beyond mammals or even dinosaursA new study published in Scientific Reports has identified evidence that Spriggina floundersi, an extinct marine organism that lived approximately 550 million years ago, favoured turning to the right. If this information is confirmed, the findings would make Spriggina floundersi the oldest known animal to display population-level ‘handedness,’ pushing the origins of left-right behavioural patterns hundreds of millions of years deeper into Earth's history than previously recognised.The discovery is based on more than 100 preserved fossils collected from Nilpena Edicara National Park and additional specimens housed at the South Australia Museum. Located in South Australia’s Flinders Ranges, Nilpena preserves one of the world’s richest fossil records from the Ediacaran Period, roughly 635-538 million years ago. It is believed that during this time life on Earth underwent a major evolutionary transition as simple multicellular organisms began developing larger bodies, bilateral symmetry and increasingly complex movement. Many researchers believe that storm events buried the entire marine communities beneath layers of sediment, thus preserving detailed impressions of organisms that lived on the ancient seafloor a few hundred million years ago.Notably, to determine whether Spriggina showed any directional preferences, scientists have carefully observed the shape and curvature of fossil impressions and found that roughly twice as many fossils appeared bent to the left as to the right. As the fossils preserve mirror-image impressions of the original animals, a leftward inclination in the rock indicates that the living animal had bent to the right. This consistent pattern suggests that Spriggina was not randomly curved by fossilisation but instead showed a directional preference during life. Researchers say that these implications extend well beyond fossil anatomy, as in many living animals consistent left-right behavioural preferences are linked to increasingly sophisticated nervous systems and specialised brain functions. According to co-author Mary Droser of the University of California, Riverside, this discovery suggests that some neurological characteristics associated with modern animals may have emerged much earlier in evolutionary history. Scientists propose that Spriggina might have possessed a relatively advanced nervous system that was capable of consistently processing environmental information in ways that favored moved toward a certain side. While scientists cannot directly observe the behaviour of the extinct organisms, the repeated pattern preserved across numerous fossils shows compelling evidence that this asymmetry reflects biology rather than a coincidence.Spriggina is among one of the earliest known animals with bilateral symmetry, meaning its body had a distinct left and right side, front and back, and top and bottom, a body plan that is shared by humans and a vast majority of animals living today. Researchers believe that this symmetry created opportunities for specialised movement, sensory processing, and behavioural preferences that eventually became widespread across the animal kingdom. Moreover, the new findings suggest that directional behavioural biases might have appeared soon after the body plan evolved, highlighting that handedness has deep evolutionary roots.The study adds to growing evidence that Ediacaran organisms were more biologically sophisticated than once believed them to be, as for decades, many researchers viewed these ancient life forms as evolutionary experiments with relatively simple anatomy. However, the discoveries of these preserved fossils from South Australia suggest that some species possessed complex body organisation, directional movement and potentially advanced sensory capabilities. Therefore, if future discoveries support these findings, Spriggina floundersi might become known not only as Earth’s earliest bilaterally symmetrical animals but also as the oldest documented ‘right-handed’ organism in history.
