Taxonomy, stratigraphy and palaeobiogeography of permianellids (Brachiopoda)

Permianellids are characterised by bilobate valves, well-developed central platform, total lack of septal apparatus and umbonal attachment. Based on the present data, four genera, namely, Dicystoconcha Termier et al. 1974; Permianella He and Zhu 1979; Litocothia Grant 1976 and Laterispina Wang and Jin 1991 are recognised and their synonyms are listed. Chronostratigraphically they range from the Kungurian to the latest Changhsingian. Palaeogeographically, permianellids are extensively found in the Palaeotethys and the transitional zones between the Palaeotethyan and Boreal Realms, and between the Palaeotethyan and Gondwanan Realms.