After Hirayama, 1997, Moody, 1997 and Lapparent de Broin, 2000

<==o †Osteopygidae [Osteopyginae sensu Hirayama, 1997]
   |--o †Lytoloma Lydekker, 1889; U. Cret. WEu.
   |  |?- †L. crassicostatum
   |  |?- †L. gosseleti
   |  |-- †L. cantabrigiense Lydekker, 1889
   |  `-- †L. elegans Bergouniouz, 1952 [L. crassa Bergouniouz, 1952]
   `--+?- †Neurochelys harvicensis
      |?- †Lophochelys
      `--+-- †Osteopygis emarginatus Cope, 1868; U.Cret.-Pal. NA. [taxonomic history]
         `--o †Erquelinnesia Hay, 1908(?); Eoc. Eu.
            |-- †E. planimentum [Lytoloma planimentum]
            `?- †E. molnaria Hay, 1908 [synon. => Osteopygis]

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