After Emig & Pardo, 2003- ["The BrachNet"], Williams, 2003, and Holmer, Popov, Streng & Miller, 2005

<==o Acrotrenida Kuhn, 1949
   |?- †Curticiidae
   |-- †Botsfordiidae [paraphyletic Acrotheloidea]
   `--+-- †Acrothelidae [paraphyletic Acrotheloidea]
      `--+-- †Paterulidae
         `--+--o Discinoidea Gray, 1840
            |  |--o Discinidae Gray, 1840
            |  |  |-- †?Discinidae genera et species indet. [L.Ord. NA. (House Formation)] [Holmer, Popov, Streng & Miller, 2005]
            |  |  |-- Discina striata (Schumacher, 1817) Lamarck, 1819
            |  |  |--o Discinisca Dall, 1871
            |  |  |  |-- D. laevis (Sowerby, 1822)
            |  |  |  |-- D. lamellosa (Broderip, 1833) [Orbicula lamellosa Broderip, 1833]
            |  |  |  |-- D. lamellosa sensu d'Hondt, 1976
            |  |  |  |-- D. rikuzenensis Hatai, 1940
            |  |  |  `-- D. tenuis (Sowerby, 1847)
            |  |  |--o Discradisca Stenzel, 1964
            |  |  |  |-- D. antillarum (d'Orbigny, 1845) [Discinisca antillarum (d'Orbigny, 1845)]
            |  |  |  |-- D. cumingi (Broderip, 1833) [Discinisca cumingi (Broderip, 1833)]
            |  |  |  |-- D. indica (Dall, 1920) [Discinisca indica Dall, 1920]
            |  |  |  |-- D. sparselineata (Dall, 1920) [Discinisca sparselineata Dall, 1920]
            |  |  |  |-- D. stella (Gould, 1862) [Discina stella Gould, 1862; Discinisca stella (Gould, 1862)]
            |  |  |  `-- D. strigata (Broderip, 1834) [Discinisca strigata (Broderip, 1833)]
            |  |  `-- Pelagodiscus atlanticus (King, 1868) Dall, 1908 [Discina atlantica King, 1868]
            |  `--+-- †Orbiculoideidae
            |     `-- †Trematidae
            `--o †Acrotretoidea Schuchert, 1893
               |-- †Eoconulidae
               `--+--+-- †Scaphelasmatidae
                  |  `-- †Torynelasmatidae
                  `--+-- †Biernatiidae
                     `--+--o †Acrotretidae Schuchert, 1893
                        |  |--o †Conotreta Walcott, 1889
                        |  |  `-- †C. millardensis Popov, Holmer & Miller, 2002
                        |  |--o †Eurytreta Rowell, 1966
                        |  |  |-- †E. curvata (Walcott, 1902)
                        |  |  |-- †E. bisecta (Matthew, 1901)
                        |  |  |-- †E. sp. cf. E. bisecta [L.Ord. NA. (House Formation)] [Holmer, Popov, Streng & Miller, 2005]
                        |  |  |-- †E. sublata
                        |  |  |-- †E. chabakovi (Lermontova in Lermontova & Razumovskii, 1933)
                        |  |  `-- †E. fillmorensis Holmer, Popov, Streng & Miller, 2005
                        |  `--o †Ottenbyella Popov & Holmer, 1994
                        |     |-- †O. carinata (Moberg & Segerberg, 1906)
                        |     |-- †O. evenda (Popov in Koneva & Popov, 1988)
                        |     `-- †O. ibexiana Holmer, Popov, Streng & Miller, 2005
                        `--+-- †Ephippelasmatidae
                           `-- †Ceratretidae

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