4.Mid- to upper Ordovician trilobite faunas from Sibumasu are strikingly similar to those of the South China plate. The fauna of the Pa Kae Formation of southern Thailand is exactly simi- lar to that of the Pagoda Limestone; Fortey (1997) listed many species in common, and three genera (Quyania, Elongatanileus, Hanjiangaspis) are not yet recorded outside