ABSTRACT
Bryozoan reefs have a lengthy geological history, from the Ordovician to the present, during which their importance fluctuated greatly (Cuffey 1977, 1985).
The earlier Mississippian (earlier Lower Carboniferous; “earlier” means Kinderhookian, Osagean, and early Meramecian, or Tournaisian and basal Viséan, in contrast to “later” for late Meramecian and Chesterian, or middle Viséan into early Namurian) was one time when bryozoanbearing bioherms were conspicuous, in the form of mud-mounds in part possibly baffled or stabilized by fenestrate bryozoans (Cuffey 1985). Larger, more complex, contemporaneous, mud-mound structures have long been known in western Europe as the Waulsortian facies (Lees 1961, Bolton et al. 1982, Lees & Miller 1985, Webb 2002). That interval saw very few cnidarian-or coelenterate-dominated reefs, because the mid-Paleozoic coral-stromatoporoid reef community had been severely diminished by the mid-Late Devonian mass extinction.
