Onychopterelloidea

Tylopterella is a genus of eurypterid, a group of extinct aquatic arthropods. Only one fossil of the single and type species, T. boylei, has been discovered in deposits of the Late Silurian period (Ludlow epoch) in Elora, Canada. The name of the genus is composed by the Ancient Greek words τύλη (), meaning "knot", and πτερόν (), meaning "wing". The species name boylei honors David Boyle, who discovered the specimen of Tylopterella.

Onychopterella ( , from Ancient Greek: ὄνῠξ (ónyx), "claw", and πτερόν (pteron), "wing") is a genus of predatory eurypterid ("sea scorpion"), an extinct group of aquatic arthropods. Fossils of Onychopterella have been discovered in deposits from the Late Ordovician to the Late Silurian. The genus contains three species: O. kokomoensis, the type species, from the Early Pridoli epoch of Indiana; O. pumilus, from the Early Llandovery epoch of Illinois, both from the United States; and O. augusti, from the Late Hirnantian to Early Rhuddanian stages of South Africa.

Onychopterellidae are an extinct family of eurypterids. The family is the only family classified as part of the superfamily Onychopterelloidea. Genera included are Onychopterella and Tylopterella.'''' Alkenopterus was once included in the Onychopterellidae but has since been classified in its own family, Alkenopteridae.''''