What is "proetidae"

Proetidae is a family of trilobites. The first species appeared in the Upper Ordovician, and the last genera survived until the Middle Permian . However, if the closely related family Phillipsiidae is actually a subfamily of Proetidae, then the proetids of Proetidae survive until the end of the Permian, where the last perish during the Permian–Triassic extinction event.