Bir fosil denizyıldızlarının köken öyküsünü yeniden şekillendiriyor

Several exceptionally preserved fossils from southwestern China are changing ideas about the early ancestry of starfish and their relatives. The 518-million-year-old animal, named Yujingia glutenotunica, measured only 8 to 22 millimetres but retained its body, gut and soft appendages. It had feather-like tentacles for collecting food particles and a second set of structures that probably anchored it temporarily to the seabed. Researchers placed Yujingia near the last common ancestor of ambulacrarians, the group containing echinoderms such as starfish and hemichordates such as acorn worms. This challenges the long-standing picture of that ancestor as a tentacle-free, burrowing worm that filtered food through its throat. Instead, complex tentacle-based feeding may have appeared early, before mineralised skeletons and other specialised echinoderm features. The conclusion combines detailed anatomy with an analysis of 505 characteristics across 100 living and extinct groups. Yujingia therefore helps bridge a major gap in the early evolutionary history of animals.