Fossil evidence for parasitic lineages are investigated including Acanthocephala, Annelida, Arthropoda, Nematoda, Nematomorpha, Pentastomida, Platyhelminthes. Despite the patchy fossil record of soft-bodied helminths, the group is more diverse than commonly assumed.Many forms have been around since the early Paleozoic already and endoparasitic lineages are present at least since the Mesozoic. See the study.