Alternative spelling: Trionychii
Parent taxon: Cryptodira according to Y. Rollot et al. 2025
See also Baur 1893, Danilov and Parham 2008, Hay 1902, Hirayama et al. 2013, Huene 1954, Jaekel 1911, Joyce 2007, Joyce et al. 2004, Joyce et al. 2004, Kato et al. 2019, Kuhn 1946, Lambe 1908, Osborn 1904, Woodward 1898 and Zittel 1890
Sister taxa: Adocusia, Carettochelyoidea, Chelonemydidae, Chelonioidea, Chelydroidea, Chersidae, Chitracephalus, Cryptoderinea, Dermatochelydidae, Dermochelyoidea, Durocryptodira, Eucryptodira, Galvechelone, Glyptopidae, Glyptopsidae, Indochelyidae, Kallokibotioninae, Kayentachelyidae, Kinosternia, Kinosternoidae, Meiolanidae, Nanhsiungchelyidae, Panchelonioidea, Pantestudinoidea, Pantrionychia, Platysternoidea, Polysternum, Selmacryptodira, Trionychidae, Trionychoidea, Tritosternidae
Subtaxa: Carettochelyidae Kappachelys Pantrionychidae
Ecology: aquatic omnivore