species have been described based on morphological variation, such that by the 1950s, as many as 70 species were recognised. Two important revisions – those of Linder in 1952 and Longhurst in 1955 – synonymised many taxa, and resulted in the recognition of only 11 species in the two genera. This taxonomy was accepted for decades, "even attaining the status of dogma". More recent studies, especially those employing molecular phylogenetics, have shown that the eleven currently recognised species conceal a greater number of reproductively isolated populations. Genera list Strudops Strud locality, Belgium, late Devonian (Fammenian) Chenops Yixian Formation, China, Early Cretaceous (Aptian) Jeholops Yixian Formation, China, Early Cretaceous (Aptian) Weichangiops Dabeigou Formation, China, Early Cretaceous Brachygastriops Dabeigou Formation, China, Early Cretaceous Lynceites Germany, Canada, Carboniferous Xinjiangiops Kelamayi Formation, China, Middle Triassic Incertae sedis species "Notostraca" minor (often referred to as Triops cancriformis minor, or "Triops" minor in historic literature) Hassberge Formation, Germany, Late Triassic (Carnian) "Notostraca" oleseni Yixian Formation, China, Early Cretaceous (Aptian) "Calmanostraca" hassbergella Hassberge Formation, Germany, Late Triassic (Carnian) See also Trilobite References External links Freshwater crustaceans Cisuralian taxonomic orders Crustacean orders Early Cretaceous taxonomic orders Early Jurassic taxonomic orders Early Triassic taxonomic orders Eocene taxonomic orders Extant Carboniferous first appearances Guadalupian taxonomic orders Holocene taxonomic orders Late Cretaceous taxonomic orders Late Jurassic taxonomic orders Late Triassic taxonomic orders Lopingian taxonomic orders Middle Jurassic taxonomic orders Middle Triassic taxonomic orders Miocene taxonomic orders Oligocene taxonomic orders Paleocene taxonomic orders Pennsylvanian taxonomic orders Pleistocene taxonomic orders Pliocene taxonomic orders