Arhropods From Annelids?

Question

Why has it been suggested that arthropods may have evolved from annelids?

Answer 1

Arthropods were once thought to have evolved from annelids as both groups have segmented bodyplans. The annelids were thought to be more primitive because they had so many similar, and unspecialized segments, while the arthropods were considered more advanced because they had segments that were differentiated for different limbs and features.

Now, though, the arthropods are no longer thought to be descended from annelids because due to genomic analysis. Because of this analysis, it's now realized that arthropods and nematodes (roundworms) are related because both groups share genes that regulate the molting of the outer cuticle, whereas the annelids are related to molluscs because both marine molluscs and polychaete annelids have planktonic "trochophore" larvae.

Answer 2

These groups have segmentation in common.