Eurypteroidea

Eurypterus ( ) is an extinct genus of eurypterid, a group of organisms commonly called "sea scorpions". The genus lived during the Silurian period, from around 432 to 418 million years ago. Eurypterus is by far the most well-studied and well-known eurypterid. Eurypterus fossil specimens probably represent more than 95% of all known eurypterid specimens.

Dolichopteridae is an extinct family of eurypterids that lived in the Silurian and Devonian periods.

Erieopterus is a genus of prehistoric eurypterid found in Silurian to Devonian-aged marine and freshwater strata of North America. The genus contains three species from the Silurian to the Devonian.'''''''' Erieopterus'' is the only genus in the family Erieopteridae, part of the Dolichopteroidea superfamily.