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Diploperculata is an
infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
of
eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is ...
s, an extinct group of aquatic
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 name, derived from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
διπλόω ("double") and ''operculum'', refers to the distinguishing feature that unites the superfamilies included in the group, that the genital operculum is made up of two fused segments. The group contains the three
eurypterine Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil deposi ...
superfamilies
Carcinosomatoidea Carcinosomatoidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of the superfamilies classified as part of the suborder Eurypterina. Some carcinosomatoid genera ...
, Adelophthalmoidea and Pterygotioidea alongside the as of yet undescribed "
waeringopteroid Waeringopteridae is a family of eurypterids, an extinct group of aquatic arthropods. The Waeringopteridae is the only family classified as part of the superfamily Waeringopteroidea, which in turn is classified within the infraorder Diploperculat ...
" clade. The diploperculate eurypterine clade had prior to its description been noted as a
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...
group of derived eurypterines that form a sister-taxon to the superfamily Eurypteroidea.


See also

*
List of eurypterid genera This list of eurypterid genera is a comprehensive listing of all genera that have ever been included in the order Eurypterida, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now consider ...


References

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