Reg. Charity No. 1168330
Although dominant at the present day, the bryozoan order Cheilostomata did not appear until the Late Jurassic. For over 55 million years after their first appearance, cheilostomes remained low in diversity and disparity, exclusively encrusting and scant in the fossil record. During the late Albian, however, cheilostomes began an explosive diversification coinciding with the appearance of several key novelties. In this paper, we describe a new monospecific cheilostome genus, Jablonskipora gen. nov. (type species Jablonskipora kidwellae gen. et sp. nov.), of importance as the oldest known cheilostome with erect growth. Jablonskipora kidwellae is a malacostegine cheilostome characterized by rigidly erect colonies with cylindrical, bifurcating branches and is moderately common in sedimentary rocks of late Albian age in south‐west England. Autozooids are dimorphic, with long tubular autozooids in the axial endozone covered by multiple layers of short, stacked, box‐shaped autozooids in the surrounding exozone. It is assigned to Chiplonkarinidae, a family now containing five genera, a tabular key for the discrimination of which is provided. The morphology of Jablonskipora and the early evolution of erect growth in cheilostomes are discussed.