They were predators ranging in size from about 4 to 9 cm (1.6 to 3.5 in) in length and lived during the Late Devonian and Early Carboniferous periods.

[1] They were some of the earliest Eucarids to develop maxillipeds, modified from the first or second thoracopods.

[1] They were originally considered eurypterids, but later their possible relationship with decapods was established.

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