Abstract

Abstract The cladid crinoid order Poteriocrinida Jaekel, 1918 is a polyphyletic group that includes a variety of independent lineages united solely by the presence of ramulate or pinnulate arms. One of these lineages is the Rutkowskicrinidae new family herein assigned to the order Dendrocrinida, Bather 1899. Genera assigned to this new family include Rutkowskicrinus new genus, Decorocrinus new genus, Iteacrinus, Nassoviocrinus, Quantoxocrinus, Sacrinus, Sostronocrinus, ?Propoteriocrinus, and ?Schmidtocrinus. Members of this family are characterized by low conical cups with ridged thecal plates, U-shaped peneplenary radial facets bearing faint transverse ridges, a proximal median ridge on the posterior side of a long, narrow, predominantly straight anal sac, and pentagonal columns with one to two cirri per nodal. Arms in this family are highly variable, ranging from isotomous to heterotomous and pinnulate. The arms in the type specimen of Rutkowskicrinus patriciae n. sp. preserve all these various arm stag...

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