Orthothecimorpha - Circothecida
Parent taxon: Orthothecimorpha according to J. J., Jr. Sepkoski 2002
Sister taxon: Exilithecida
Subtaxa: Arathecus Asijatheca Costatheca Extentitheca Kunyangotheca Ladatheca Leibotheca Mojczatheca Spinulitheca Turcuthecidae Uniformitheca
Ecology: stationary epifaunal suspension feeder
Distribution:
• Ordovician of Poland (1 collection)
• Cambrian of Australia (21), Canada (44: Newfoundland and Labrador, Nova Scotia), China (9), Iran (3), Kazakhstan (17), Kyrgyzstan (2), Norway (2), the Russian Federation (36), Saint Pierre and Miquelon (1), the United Kingdom (2), United States (4: Massachusetts, Nevada)
• Placentian of Canada (2: Newfoundland and Labrador, Nova Scotia), United States (4: Massachusetts)
• Ediacaran of United States (1: Nevada)
Total: 149 collections including 189 occurrences