Ancient critter could be the granddaddy of shellfish


A weird marine creature that lived 500 million years ago at a time of explosive growth in Earth’s biodiversity could be a forerunner of worms and mollusks, a study published Thursday says.

Paleontologists from both China and Europe have taken a second look at fossils of a species called Cotyledion tylodes, a small animal that when it was identified in 1999 was thought to be a cnidarian, or part of a group of jellyfishlike species.

C. tylodes had a goblet-shaped body between 8 and 56 mm long, with a cup-shaped upper part and lower cylindrical stalk.

On the upper part, the creature’s mouth lay adjacent to its anus, with the two organs connected by a U-shaped gut and encircled by a “crown” of foldable tentacles, the scientists found.

The creature’s peculiar anatomy means that C. tylodes is most probably an entoproct, meaning an organism that strains seawater to filter out suspended food particles.

If so, its place in the family tree is wrong, the new study says.

It is likely to be a primitive lophotrochozoan, a branch that today includes worms and shellfish.

The study appears in the Nature Publishing Group journal Scientific Reports.