A weird sea creature was anatomically unlike anything ever seen — flipping it around led to a revelation

An extinct sea creature resembling a ribbon has been identified as one of the earliest animals to evolve a precursor of a backbone. The discovery was made by scientists who turned the fossil of the creature, called Pikaia, upside down and found its nerve cord. Previous studies had misinterpreted the animal’s dorsal organ as a blood vessel, but it was actually its gut. The new understanding places Pikaia as part of the foundational lineage of all chordates, including vertebrates. The discovery sheds new light on the anatomy of Pikaia and its place in the evolutionary tree.