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Periarchus
Taxonomy
Periarchus was named by Conrad (1866) [Sepkoski's age data: T Eo-m-u T Eo-u].
It was assigned to Scutellidae by Clark and Twitchell (1915), Cooke (1942); to Protoscutellidae by Durham (1955), Durham (1966), Kier (1968), Kier (1997); and to Clypeasteroida by Sepkoski (2002).
It was assigned to Scutellidae by Clark and Twitchell (1915), Cooke (1942); to Protoscutellidae by Durham (1955), Durham (1966), Kier (1968), Kier (1997); and to Clypeasteroida by Sepkoski (2002).