Haplodrili
| Haplodrili Temporal range: Cambrian (or earlier?) - present | |
|---|---|
| An image of Polygordius appendiculatus, an archiannelid species. | |
| Scientific classification | |
| Domain: | Eukaryota | 
| Kingdom: | Animalia | 
| Phylum: | Annelida | 
| Class: | Polychaeta | 
| Order: | Haplodrili Lankester, unknown date | 
| Families | |
| Dinophilidae | |
| Synonyms | |
| Archiannelida Hatschek, 1878 | |
Haplodrili, or Archiannelida, is an order of primitive polychaete worms. Zoologist Ray Lankester gave it the name haplodrili, while zoologist Berthold Hatschek later named it Archiannelida. Once considered to be a class under Annelida, and even a separate phylum, Haplodrili is now widely accepted to be an order under Polychaeta. Species in this order are known for completely lacking external segments.