This page represents the following TreeOfLife-200M taxonomic path.[1]
Amphithelion is treated here as a fossil/cosmopolitan genus within Scleritodermidae, historically associated with Rhizomorina-type lithistid-related demosponges that often form funnel-like to flabellate (fan- or leaf-like) growth forms in reconstruction. In the taxonomic framework summarized by the cited literature, Amphithelion placements have been unstable because many of the characters proposed for separating closely related fossil taxa are sensitive to preservation and to how soft-part canalization maps onto skeletal architecture; consequently, overall habitus and the broad skeletal framework are often emphasized over fine, preservation-dependent distinctions.
GBIF currently lists Amphithelion as an accepted genus-level taxon (authorship Zittel, 1878) within Scleritodermidae.[2]
In a dedicated reassessment of fossil “Rhizomorina” demosponges, Amphithelion (Zittel) is highlighted as a historically shifting taxon: it was treated at times as possibly subgeneric by Zittel, later synonymized with Verruculina by multiple authors, and subsequently re-split in later classifications into multiple genera and families. Despite these taxonomic reorganizations, the included taxa are characterized as essentially similar overall in habitus (including funnel-like/flabellate variants), general skeletal framework, and pore/oscule-related features.
Within the referenced systematic framework, the family-level treatment of scleritodermatids emphasizes skeletal microarchitecture and skeletal texture: the family is used as the taxonomic “home” for Rhizomorina taxa that show (or plausibly resemble) truly fibrous skeletal structures, contrasted with other Rhizomorina types that are compact or only semi-fibrous.