Late Cretaceous-Paleocene “porinids” – mixed frontal shields and evidence of polyphyly

Putative porinids (cheilostomata) from the Late Cretaceous and Paleocene of north western Europe and the USA exhibit a varied range of external frontal-shield morphologies. Some frontal shields are relatively featureless or merely dimpled; others have numerous foramina of various diameters and these are surrounded by raised ridges in some species. The complex surface topography of some frontal shields defies interpretation when viewed externally but exceptional preservation of many taxa allows fracture of zooids and SEM observation of frontal-shield interiors. A number of species have umbonuloid shields whereas others have frontally concealed spinocysts of well-developed costae. External foramina in many species correspond to frontally opening areolar septular-pore canals, spiramina, and loci of avicularia. All the species examined are unrelated to Recent Porina gracilis , the type species of the family, with a pseudoporous frontal shield and lepralioid ascus sac. Among the taxa now excluded from the Porinidae, Pachythecella is restricted to its type species, the balance of species attributed to it being transferred to Frurlonella (Lepraliellidae). Spiraminate, umbonuloid-shieldedPachyfheceZ/a, Beisselina , and Pachydermopora governor. are included in the Tessarado- midae. Spiraminate Colwnnotheca, Diplobeisselina , and Scoriopora gen. nov. have a primary spinocystal shield of large costae. For these genera a new family) Scorioporidae, and superfamily, Scorioporoidea, are proposed.