Although some late Ediacaran fossils may represent annelids, the oldest known fossil that is identified with confidence comes from about 518 million years ago in the early Cambrian period. Fossils of most modern mobile polychaete groups appeared by the end of the Carboniferous, about 299 million years ago.

Where did annelids come from?

The oldest fossil annelids come from the Early Cambrian Sirius Passet and Guanshan biotas and Middle Cambrian Burgess Shale.

What feature appeared first in annelids?

Coelom. An important evolutionary development in annelids, that is not obvious when you see the animal from the outside, is the presence of a well-developed coelom, or body cavity. Along with mollusks, annelids are among the first animals to have a coelom.