Parent taxon: Asaphida according to R. A. Fortey and D. L. Bruton 2013
See also Adrain 2011
Sister taxa: Aethodionide, Anomocarellidae, Anomocaridae, Anomocaroidea, Asaphina, Asaphoidea, Dikelocephaloidea, Eurekiidae, Hungaiidae, Ordosiidae, Parabumasttides, Pseudocyclopyge, Pterocephalidae, Remopleuridae, Rhyssometopidae, Trinucleoidea
Subtaxa: Cyclopygidae Nileidae Symphysurinidae Taihungshaniidae
Type: Cyclopygidae
Ecology: fast-moving low-level epifaunal carnivore
Distribution:
• Uhaku of Sweden (5 collections)
• Dobrotivian of Czechia (2), France (1), Morocco (1), Portugal (1), Spain (3)
• Liben of Czechia (2)
• Letna of Czechia (1)
• Whiterockian of Canada (24: Newfoundland, Newfoundland and Labrador), Norway (4), United States (29: Nevada, Oklahoma, Utah)
• Chazyan of Canada (4: Newfoundland and Labrador)
• Langevoja of Sweden (4)
• Hunderum of Sweden (6)
• Billingen of Norway (1), Sweden (7)
• Arenigian of Canada (2: Northwest Territories), China (21)
• Klabava of Czechia (1), France (1)
• Arenig of Argentina (3), Bolivia (1), China (65), France (5), Iran (1), Morocco (1), Norway (4), the Russian Federation (1), Spain (1), Sweden (5), the United Kingdom (6)
• Dawan of China (4)
• Ordovician of Argentina (12), Australia (2), Canada (62: Alberta, British Columbia, Newfoundland, Newfoundland and Labrador, Northwest Territories, Quebec, Yukon), China (156), Colombia (1), Czechia (17), Estonia (1), France (12), Greenland (4), Iran (12), Ireland (10), Italy (3), Kazakhstan (8), Morocco (3), Norway (19), Oman (1), the Russian Federation (23), Spain (1), Sweden (46), the United Kingdom (50), United States (66: Alaska, British Columbia, California, Idaho, Maine, Montana, Nevada, New Mexico, New York, Oklahoma, Texas, Utah, Vermont, Virginia)
• Ibexian of United States (3: California, Nevada)
• Skullrockian of Canada (22: British Columbia, Newfoundland), Greenland (1), United States (25: New York, Texas, Utah)
• Cambrian to Ordovician of Argentina (1), Canada (1: Quebec), the Russian Federation (1)
• Cambrian of Canada (4: Newfoundland and Labrador), China (10), the Russian Federation (3), United States (10: Texas, Utah)
Total: 807 collections including 1156 occurrences