| To tease out the details of the transition, other researchers recently turned to lancelets, vertebrates' closest spineless relatives. |
| In lancelets, the trunk somites extend and fuse ventrally to give the unsegmented periviscelar coelom. |
| Fishes of the western North Atlantic, Lancelets, cyclostomes, and sharks. |
| Unlike lancelets, however, Haikouella possessed a small number of pharyngeal bars that may have been composed of mucocartilage, as in modern lampreys. |
