Ordovician plectambonitacean brachiopods from New South Wales

Abstract

Representatives of the brachiopod superfamily Plectambonitacea Jones 1928 are described and illustrated from Late Ordovician (Caradoc) formations of New South Wales. Two new genera, Gunningblandella (a sowerbyellid, with type species G. resupinata sp. nov.), and Durranella, represented by type species D. septata sp. nov., and D. rugosa sp. nov., are introduced. The family Anoptambonitidae R[otilde][otilde]musoks 1963 is emended to include Durranella, Kassinella Borisyak, Chaganella Nikitin, Trimurellina Mitchell, and possibly Xenambonites Cooper, in addition to Anoptambonites Williams. Other new species described are Dulankarella? partita (Leptellinidae), Sowerbyites vesciseptus (Leptestiidae), Sowerbyella lepta, Sericoidea sejuncta and Sericoidea minor (Sowerbyellidae) and Kassinella anisa.

Interpretation of functional morphology of these species supports reconstruction of the plectambonitacean schizolophe in a position largely anterior to the dorsal muscle field. Feeding current directions are inferred from distribution of marginal setal grooves and internal ridge/channel systems. In general, inhalant currents entered the shell anterolaterally and laterally, being exhausted medially and/or posterolaterally. Species of Sericoidea and Sowerbyella described here occur in deep-water graptolitic sediments and display morphological adaptations consistent with either an epiplanktic habit, or attachment to localised firm substrates on or slightly above the sea floor.