The microcrinoid taxonomy, biostratigraphy and correlation of the upper Fredericksburg and lower Washita groups (Cretaceous, middle Albian to lower Cenomanian) of northern Texas and southern Oklahoma, USA

The stratigraphy of the upper Fredericksburg and lower Washita groups northern Texas southern Oklahoma is described, biostratigraphical correlation within region, further afield, using microcrinoids, ammonites, planktonic foraminiferans inoceramid bivalves summarised. taxonomy roveacrind microcrinoids revised by senior author, a new genus, Peckicrinus , with type species Poecilocrinus porcatus (Peck, 1943). New include Roveacrinus proteus sp. nov., R. morganae Plotocrinus reidi Pl. molineuxae rashallae nov. Styracocrinus thomasae formae genus Peck, 1943 are Po. dispandus forma floriformis discus Euglyphocrinus Gale, 2019 E. pyramidalis 1943) radix pentaspinus genera 1943, Douglas, 1908 form branching phylogenetic lineage extending from middle Albian into Cenomanian, showing rapid speciation, upon which roveacrinid zonation for (zones AlR1–12) largely based. Outside Oklahoma, zone AlR1 recorded Aube (southeastern France) zones AlR11–CeR2 Agadir Basin in Morocco central Tunisia. It likely that will be widely applicable to Cenomanian successions many other regions.