ABSTRACT
Cretaceous rocks of the epicontinental Western Interior Seaway (WIS) of North America have yielded few bryozoans, despite the profusion of other marine groups. Nevertheless, stratigraphical and palaeoecological papers published by the late Don Hattin mention and figure abundant bryozoans from the Turonian Fairport Member of the Carlile Shale in west-central Kansas. Taxonomic study of material collected by Hattin from seven localities reveals the presence of just three bryozoan species, one cyclostome (Oncousoecia defluxima sp. nov.) and two cheilostomes (Iyarispora hattini sp. nov. and Marginaria sparsa sp. nov.). All encrust the exterior surfaces of inoceramid bivalves. Colonies of the oligoserial cyclostome O. defluxima are notable in exhibiting profuse evidence for in-vivo damage and reparative growth. Whereas previously described cheilostomes from the WIS are overwhelmingly non-ovicellate malacostegines, including the Carlile Shale electrid I. hattini, M. sparsa is unusual in being only the second known WIS ovicellate cheilostome. The dominance of malacostegines in the WIS compared to Late Cretaceous deposits elsewhere is postulated to result from their superior dispersal and ability to recolonize after deoxygenation events in this epicontinental water mass.
ZooBank registration: zoobank.org:pub:B211B8CC-F58A-49A3-B3D3-E4DEF49A5896
