Heptagenioidea

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Subclassis: Pterygota
Ordo: Ephemeroptera
Subordo: Pisciformia
Superfamilia: Heptagenioidea
Familiae: Coloburiscidae - Oligoneuriidae - Isonychiidae - Heptageniidae
Fossil familiae

†Aenigmephemeridae - †Epeoromimidae

Heptagenioidea is a superfamily of mayflies. Members of this superfamily are found in most parts of the world apart from the Arctic and Antarctic, with Heptageniidae being the most widely distributed family.

Heptagenioidea probably originated in the Jurassic period when mayflies started breeding in flowing water, the mouthparts and forelegs becoming adapted to passive feeding. The ancestors of the new group had bred in still water, and the opportunities provided by the change in environment encouraged rapid radiation.[1]
References

Tercedor (1991). Overview and Strategies of Ephemeroptera and Plecoptera. CRC Press. p. 91. ISBN 978-1-877743-08-5.