The First Pennsylvanian Batocrinid and Other New Echinoderms from the Minturn Formation of Central Colorado

Middle Pennsylvanian (latest Atokan) strata in the Minturn Formation of north-central Colorado have yielded new specimens of echinoderms, which have not been previously described from the area. Eretmocrinus sawdoi, new species, is the first batocrinid known from the Pennsylvanian. The Batocrinidae (a family of camerate crinoids) were previously thought to have become extinct during the Mississippian. A probable codiacrinid and an unidentified, upflared, infrabasal circlet are additions to the Minturn crinoid fauna. These specimens show that the crinoid fauna is more diverse than previously thought. New specimens of Ulocrinus rockymontanus Strimple and Moore, 1973, Aglaocrinus magnus (Strimple, 1949), and the columnal taxon Pentaridica pentagonalis Moore and Jeffords, 1968, provide new morphological information. Additional specimens of echinoid plates and spines have also been recovered from the Minturn Formation. They are assigned to Archaeocidaris ourayensis Girty, 1903, Archaeocidaris triplex White, 1881, and Archaeocidaris cratis White, 1876. These specimens come from three thin marine intervals that are overlain and underlain by coarse fluvial and marginal marine deposits. They were recovered from shale and limestone beds that interfinger with sandstone and shale beds. Thus, the echinoderms were living in areas that experienced frequent influxes of siliciclastic detritus.