Various classifications of Dicyemida in previous studies
Past studies used limited data to attempt to classify Dicyemida and they disagreed on the exact position. The left figure represents the classification scheme from a paper published in 1996 that names the Dicyemida as part of a sister group to Spiralia and close to Ecdysozoa, which contain centipedes and nematodes. The middle figure represents a paper from 2010 that places the Dicyemida within the Spiralia group, but closely related to Annelida, which includes earthworms and leeches. The right figure represents another study from 2010 that places the Dicyemida further from the Annelida, with Mollusca—snails, slugs, squid, etc—between them.