| Stylonuridae, Stylonurina, Mixopterus|
Mixopteridae is a family of extinct eurypterids found in Late Silurian marine strata.
Mixopterids were characterized by large exoskeletons with scattered tubecules or semicircular scales. The prosoma (head) was subquadrate, protruding antemedially. The chelicerae (claws in front of the mouth) were small. The first two pairs of walking legs were strongly developed, with long paired spines. The third and fourth walking legs were moderately sized, with short spines. The preabdomen, the front portion of the body, was narrow with axial furrows, while the postabdomen was narrow. The telson was a curved spine.Class Merostomata Dana, 1852
Subclass Eurypterida Burmeister, 1843
Superfamily Eurypteracea Burmeister, 1845
Family Mixopteridae Caster & Kjellesvig-Waering, 1955
Genus Mixopterus Ruedemann, 1921
Genus Lanarkopterus(Størmer, 1936)