A Late Jurassic Boreal echinoderm Lagerstätte from Janusfjellet, central Spitsbergen, Arctic Norway

Abstract

A well preserved, low diversity assemblage of fossil echinoderms is described from the Volgian Slottsmøya Member (Agardhfjellet Formation) on central Spitsbergen. Five species are recognized: the isocrinid Chariocrinus sp. A, the pedinoid Hemipedina sp. A, the forcipulate asteroid Asteriidae sp. A, the ophiacanthid Ophiotreta sp. A and the ophiurid Ophiurinae sp. A. A depositional environment model reconciling autecologic, taphonomic and sedimentary evidence is presented. The Janusfjellet Lagerstätte was formed by a single, rapid burial event during a storm, which entombed together autochthonous asteroids and ophiuroids and allochthonous crinoids and echinoids on a dysoxic muddy seafloor. Comparable echinoderm material from the Boreal Late Jurassic—Early Cretaceous is scarce, outdated and usually poorly described and illustrated. The scarcity of reported occurrences probably results from a collector bias for rare complete specimens and does not reflect the true echinoderm composition of Mesozoic high-latitude communities.