Article: Extraordinarily early Venus' flower basket sponges (Hexactinellida, Euplectellidae) from the uppermost Ordovician Anji Biota, China

Abstract The deep-sea hexactinellid sponge Euplectella is an iconic living genus with no known fossil record. The family Euplectellidae (which includes a subset of genera that share the common name ‘Venus' flower basket’) has a very sparse record from the Middle Cretaceous onwards, and an estimated crown-group origin at around 300 Ma based on molecular clocks. New material of Venus' flower baskets from the latest Ordovician Anji Biota of China (444 Ma) dramatically extends the known and predicted range of the group, with implications for the diversification of the class Hexactinellida and the timing of development of deep-sea ecosystems. The new material is described as Anjiplectella davidipharus gen. et sp. nov., with an additional taxon remaining in open nomenclature but demonstrating diversification within the group by this time.