Trilobita - Asaphida - Ptychaspididae
Parent taxon: Dikelocephalacea according to J. D. Loch and J. F. Taylor 2004
See also Adrain 2011 and Whittington et al. 1997
Sister taxa: Dikelocephalidae, Dikelocephaliidae
Subtaxa: Alborsella Changia Eoptychaspis Eowuhuia Euptychaspis Idiomesus Imlerella Kathleenella Keithia Keithiella Macronoda Plectrella Proricephalus Ptychaspis Saukioides Sunwaptia Wilcoxaspis
Ecology: fast-moving low-level epifaunal carnivore
Distribution:
• Ordovician of Australia (1 collection), Canada (3: Newfoundland and Labrador, Yukon)
• Tremadoc of China (1)
• Skullrockian of United States (1: Texas)
• Cambrian of Australia (5), Canada (46: Alberta, Newfoundland and Labrador, Quebec, Yukon), China (5), Iran (2), South Korea (6), United States (81: Idaho, Minnesota, Montana, Nevada, New Mexico, New York, Pennsylvania, South Dakota, Texas, Utah, Vermont, Wisconsin)
• Taoyuanian of China (2), Turkey (1)
Total: 154 collections including 260 occurrences