A small wormlike creature called Spriggina floundersi, dated to roughly 550 to 560 million years ago, may be the earliest animal ever recorded showing a consistent left-or-right bias. Spriggina lived during the Ediacaran Period, a quiet chapter of Earth’s history that preceded the Cambrian Explosion, when most major animal groups suddenly appeared in the fossil record. It was South Australia’s chosen state fossil, and now it has earned a new kind of fame.
Right-handedness, as we know it, is about having a preferred limb. Spriggina had none. So what did researchers actually observe? By examining many fossil specimens collected from the same beds in South Australia, paleontologists found that the animals preserved their bodies curved in a consistent direction — almost all turning the same way when they moved. That repeated directional preference is what counts as behavioral handedness: a repeatable bias toward one side, even without limbs to favor.
Why does this matter? Handedness is usually thought of as a product of a complex, asymmetric brain — a feature of vertebrates and some advanced invertebrates. Finding a left-right movement bias in a creature that existed before brains, jaws, eyes, or muscles as we know them pushes the origin of such bias far deeper into animal history. It suggests that even the simplest early animals may have developed a stable “favorite side,” and that the neural wiring for asymmetry might be one of the oldest legacies of the animal body plan.
The discovery also highlights how much the Ediacaran world still has to teach us. These soft-bodied fossils rarely preserve fine detail, so any behavioral signal trapped in stone is unusually precious. A centimeter of fossilized worm is enough to rewrite a tiny piece of evolutionary history.
The knowledge takeaway: the oldest evidence of a consistent “right-handed” bias comes from a wormlike Ediacaran fossil called Spriggina floundersi, which lived about 550 million years ago and had no hands at all. Handedness may be far older and more fundamental to animal life than we assumed.