Kukrusecrinus stellatus gen. et sp. nov.—the First Representative of the Family, Colpodecrinidae (Crinoidea, Camerata) in the Baltic Ordovician, Its Paleobiogeographic Significance and the Family Phylogenetic Position

The calyx of a new genus and species, Kukrusecrinus stellatus from the Kukruse Regional Stage (Sandbian Upper Ordovician) of Northern Estonia, close to Colpodecrinus from the Bromide Formation (Sandbian) of North America, is described in detail. A fragment of Kukrusecrinus sp. is also described from the Ukhaku Regional Stage (Darriwilian). These echinoderm finds indicate the presence of biogeographical connections between Baltica and Laurentia in the second half of the Middle Ordovician (Late Darriwilian). The composition of the family Colpodecrinidae Sprinkle et Kolata, 1982 and its possible phylogenetic relationships with other Ordovician crinoids are considered, based on the reconstruction of the morphogenesis of unusual key features of the family.