Eurypterid
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Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the order Eurypterida. The earliest known eurypterids date to the Tremadocian stage of the Ordovi
Eurypterus remipes 001
Illustration of Hibbertopterus, a large stylonurine (lacking swimming paddles) eurypterid
The holotype of Palmichnium kosinkiorum, containing the largest eurypterid footprints known
The supposed "gill tracts" of eurypterids have been compared to the air-breathing pseudotracheae present in the posterior legs of modern isopods, such as Oniscus (pictured).
Dekatriata
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Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterida and additionally two stem-genera Winneshiekia and Houia. Dekatriata is defined by an opis
Eurypterid
…ancestor) and thus not a valid phylogenetic group. Eurypterids were recovered as closely related to arachnids instead of xiphosurans, forming the group Sclerophorata within the clade Dekatriata (composed of sclerophorates and chasmataspidids). Lamsdell noted that it is possible that Dekatriata is synonymous with…
Eurypterus remipes
Araneus diadematus 257107384