Brachiopods associated with stromatoporoid mounds from the Middle to Upper Ordovician Cashions Creek Limestone, Tasmania

Stromatoporoid mounds and inter-mound carbonates in the upper part of the Darriwilian to Sandbian (Middle - Upper Ordovician) Cashions Creek Limestone in the Florentine Valley, southwest-central Tasmania were sampled in order to document the benthic macrofauna and investigate whether the stromatoporoid mounds had a higher brachiopod biodiversity. The brachiopod assemblage is characterised by 'Lepidomena' with a relative abundance of about 55% of the fauna. 'Lepidomena fortimuscula' and 'Lepidomena pulchra' represent the key brachiopod species. The brachiopod diversity recorded is higher in the inter-mound than on the mound. Other macrofossil groups, including bivalves, rostroconchs, cephalopods, bryozoans, gastropods and echinoderms are characterised by low diversity. Gastropods and brachiopods are the main encrusting organisms on the mounds, with encrusting bivalves and rostroconchs a minor component. The fauna is interpreted to have existed in a shallow marine, high energy depositional environment.