"Attercopus fimbriunguis", from in the Devonian period, bears the earliest known silk-producing spigots, and was therefore hailed as a spider, but it lacked spinnerets and hence was not a true spider. Rather, it was likely sister group to the spiders, a clade which has been named Serikodiastida. Close relatives of the group survived through to the Cretaceous Period. Several Carboniferous spiders were members of the Mesothelae, a primitive group now represented only by the Liphistiidae, and fossils suggest taxa closely related to the spiders, but which were not true members of the group were also present during this Period.