Abstract
A crinoid and stelleroid fauna is described from the Famennian (Late Devonian) Broken Rib Member of the Dyer Formation of the White River Plateau, Colorado. The fauna postdates the Late Devonian extinction event. Six new crinoid species described, including the new genus Tarassocrinus, are: Strimplecrinus dyerensis, Catactocrinus? torus, Hypselocrinus? bisonensis, Gilmocrinus? albus, Eireocrinus? coloradoensis, and Tarassocrinus synchlydus. The cladid-dominated crinoid fauna is transitional between earlier Devonian and later Carboniferous faunas. It contains the first report of Cupressocrinites (a Famennian Lazarus taxon) and Eireocrinus? in North America and extends ranges of several Carboniferous genera into the Late Devonian. A preliminary revision of the Rhenocrinidae is recommended. The family Glossocrinidae is recognized, and the Cupressocrinitidae are transferred to the Gasterocomacea. A new stelleroid genus and species, Pleiadeaster inceptus (Asteroidea; family unknown), and an ophiuroid, Ophiopolytretus aethus (Ophiuroidea; Lapworthuridae?) are named. In addition, Hudsonaster (Hudsonasteridae; Asteroidea) and two unassigned asteroids are present, and three further stelleroids cannot be assigned to the class level. Pleiadeaster and Hudsonaster are important because they suggest that the Late Devonian might have been a time of transition for asteroids. Ophiopolytretus aethus is an oegophiurid ophiuroid with distinctive respiratory? pores penetrating the disk plates.
