A 555-million-year-old worm-like creature displayed a bias toward turning right, according to a new analysis of fossils from South Australia. The finding offers the earliest known evidence of handedness in animals.
Researchers examined 100 specimens of Spriggina floundersi, a small flatworm that lived on the seafloor during the Ediacaran Period. Scott Evans of the American Museum of Natural History led the study, which found that twice as many fossils were bent in a way indicating the animals turned right rather than left.
Evans noted that the pattern is statistically significant and aligns with observations of handedness in modern animals. Some specimens showed bends in both directions, suggesting the creatures could move freely without circling.
The discovery indicates that aspects of advanced nervous systems, such as favouring one side of the body, emerged before the Cambrian Period. Russell Bicknell of Flinders University said the presence of such functional asymmetry deep in the fossil record provides key insights into the evolution of these behaviours.
