Artiopoda - Agnostida - Metagnostidae
Synonyms: Arthrorhachidae Raymond 1913, Geragnostidae Howell 1935, Geragnostinae Howell 1935, Trinodidae Howell 1935
Parent taxon: Condylopygoidea according to E. B. Naimark and T. V. Pegel 2017
See also Harrington and Leanza 1957, Hoel 1999, Jell and Adrain 2002, Owens and Fortey 2009, Robison and Pantoja-Alor 1968 and Whittington et al. 1997
Sister taxa: Agnostidae, Ammagnostidae, Clavagnostidae, Condylopygidae, Diplagnostidae, Doryagnostidae, Glaberagnostus, Glyptagnostus, Leiagnostus, Megagnostus, Phalacromidae, Phalagnostus, Phaldagnostus, Pseudagnostidae, Ptychagnostidae, Spinagnostidae, Valenagnostus
Subtaxa: Anglagnostus Arthrorhachis Chatkalagnostus Corrugatagnostus Dividuagnostus Galbagnostus Geragnostella Geragnostus Granuloagnostus Homagnostoides Trinodus
Ecology: slow-moving epifaunal detritivore
Distribution:
• Dobrotivian of the Czech Republic (2 collections), Portugal (1)
• Uhaku of Sweden (1)
• Chazyan of Canada (5: Newfoundland and Labrador)
• Whiterockian of Canada (10: Newfoundland and Labrador), United States (2: Nevada)
• Fennian of France (1), United States (1: Nevada)
• Volkhov of Sweden (4)
• Arenig of Bolivia (1), Canada (2: Newfoundland and Labrador), China (11), France (2), Sweden (4), the United Kingdom (5)
• Klabava of the Czech Republic (2), France (1)
• Dawan of China (2)
• Arenigian of Argentina (1), China (21), France (2)
• Ordovician of Argentina (13), Australia (9), Belgium (2), Canada (7: Alberta, Newfoundland, Newfoundland and Labrador, Northwest Territories, Northwest Terrorities, Yukon), China (64), the Czech Republic (7), Denmark (3), Estonia (2), France (3), Iran (1), Ireland (8), Italy (2), Kazakhstan (1), Morocco (1), Norway (20), Poland (1), the Russian Federation (8), Spain (3), Sweden (54), the United Kingdom (29), United States (39: California, Maine, Montana, Nevada, New Mexico, Oklahoma, Texas, Utah, Virginia)
• Cressagian of the United Kingdom (1)
• Tremadoc of Argentina (43), China (17), Colombia (1), the Czech Republic (3), France (5), Iran (1), Mexico (1), Spain (3), Sweden (2), United States (2: Montana, Vermont)
• Skullrockian of Argentina (1)
• Ibexian of Norway (1), United States (1: California)
• Cambrian of Australia (1), Canada (1: Newfoundland and Labrador), China (5), United States (10: Alaska, Montana, Nevada, New Mexico, Texas, Utah)
Total: 457 collections including 555 occurrences