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550‑Million‑Year‑Old Worm Shows Population‑Level Right Turn Preference

Researchers say the pattern points to early left–right body asymmetry and coordinated movement that could reflect more complex sensory or nerve‑to‑muscle control than previously recognized.

Overview

  • A peer‑reviewed study published in July 2026 examined more than 100 Spriggina floundersi fossils and found roughly twice as many left‑curved impressions in the rock, which—because the fossils are mirror‑image imprints—indicates a rightward bend in life.
  • The team used bed‑scale mapping, variation in individual orientations, and comparisons across slabs to test and reject simple environmental causes such as consistent currents or post‑burial drying as explanations for the bias.
  • Authors interpret the bias as population‑level handedness and evidence that Spriggina could wriggle and change direction, but they acknowledge no nervous tissue is preserved so claims about neural complexity remain inferential and debated.
  • The analysis appears in Scientific Reports (DOI 10.1038/s41598-026-53857-x), was led by researchers at the American Museum of Natural History with collaborators from multiple universities, and drew on museum collections and Nilpena field beds.
  • If confirmed, the result shifts the origin of coordinated lateralized behavior and bilateral asymmetry back into the Ediacaran and suggests the anatomical and behavioral groundwork for later Cambrian animal diversification was already present more than half a billion years ago.