The Hardieopteridae are a family of

eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 Myr, million yea ...

s, an extinct group of

chelicerate The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It contains the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mite ...

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s commonly known as "sea scorpions". The family is one of two families contained in the superfamily

Kokomopteroidea Kokomopteroidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of four superfamilies classified as part of the suborder Stylonurina. Kokomopteroids have been recov ...

(along with Kokomopteridae), which in turn is one of four superfamilies classified as part of the suborder

Stylonurina Stylonurina is one of two suborders of eurypterids, a group of extinct arthropods commonly known as "sea scorpions". Members of the suborder are collectively and informally known as "stylonurine eurypterids" or "stylonurines". They are known from ...

. Hardieopterids have been recovered from deposits of Early Silurian to

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...

age in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

. Hardieopterids are defined as kokomopteroids with lateral pleurae on their metastoma and pretelson, large lunate scales on the posterior margin of the carapace and a clavate telson. The opisthosoma shows both a second and fourth order differentiation into a mesosoma and metasoma. Appendages II-IV are unknown, though appendage V is spiniferous and VI is non-spiniferous as in the genus '' Hardieopterus''. The Hardieopteridae display some adaptations towards sweep-feeding, such as a broadening of the metastoma and the spines of the anterior prosomal appendages and may even have been

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

bottomdwellers living partially buried in the substrate.

Genera

Family Hardieopteridae Tollerton, 1989 * '' Hallipterus'' Kjellesvig-Waering, 1963 * '' Hardieopterus'' Waterston, 1979 * ''

Tarsopterella ''Tarsopterella'' is a genus of prehistoric eurypterid classified within the family Hardieopteridae. It contains only one species, ''T. scotica'' from the Lower Devonian of Scotland Scotland (, ) is a country that is part of the United K ...

'' Størmer, 1951

References

Stylonurina Prehistoric arthropod families Silurian first appearances Devonian extinctions {{eurypterid-stub