The oldest bryozoans: new evidence from the early ordovician.
An abundant, previously problematic fossil from the Lower Ordovician (Canadian) Black Rock limestone of the Ozark Uplift area is an undescribed dianulitid bryozoan. It is believed to be the oldest unquestionable bryozoan known. The growth morphology varies widely and is believed to be environmentally influenced.
McLeod
J D
JD