Evolution

This is a general map of the evolutionary tree of life.

As you can see, annelids appeared pretty early on.

However, it is difficult to obtain an exact map of classification in terms of all the branches of the annelid family, which many scientists are still working on today. There are hot debates over which subgroups should belong to which branch, based on the smallest changes derived from the fossil record and from genetic profiling.

A generally accepted anscestor of the phylum annelida is the deuterostomes, which split into several branches. A split of the child branches would be the relationship of phylum annelida to the deuterostomes.

This tree shows the various families that are found in polychaetes.

The major adaptations for the annelids are a segmented body plan, and the presence of setae.