Five species of "Pterygotus" have been discovered in deposits of Silurian age in the Welsh Borderland, "P. ludensis", "P. arcuatus", "P. grandidentatus", "P. lightbodyi" and "P. denticulatus". The Welsh Borderland preserves one of the more extensive eurypterid faunas known, with the exact genera and species depending on the precise time. The Wenlock-aged "P. grandidentatus" occurred together with "Mixopterus", "P. arcuatus" of Middle Ludlow age occurred together with "Salteropterus", "Erettopterus" and "Carcinosoma" whilst "P. lightbodyi" and "P. denticulatus" were contemporaries with each other and species of the genera "Erettopterus" and "Carcinosoma". "P. ludensis", Downtonian in age, occurred together with a diverse array of eurypterids composed of "Carcinosoma", "Dolichopterus", "Erettopterus", "Hughmilleria", "Parahughmilleria", "Eurypterus", "Nanahughmilleria", "Marsupipterus", "Stylonurus", "Tarsopterella", "Slimonia" and "Salteropterus".