Lower Devonian Chonetoidean Brachiopods From Bac Bo, North Viêt Nam

Abstract

Recent investigations of the Lower Devonian fauna of North Viêt Nam have provided abundant invertebrates, among which chonetoidean brachiopods are especially common. Their good preservation has allowed the revision of eight of the nine species described in the literature. The North Vietnamese chonetoidean fauna is mainly characterized by the diversity of representatives of the Family Strophochonetidae (strophochonetines and parachonetines), which includes nine species. Three new genera, namely TulynetesBacbonetesCyrtochonetes, and two species, namely Bacbonetes janvieriChlupacina nariensis, are described. The occurrence of Perichonetes mirabilisChlupacina nariensis, and plicanoplitid brachiopods establishes the extension of the south-west China pelagic Nandan Facies to eastern Bac Bo. The Lower Devonian chonetoidean fauna of eastern Bac Bo is closely allied to that of south-west and central China belonging to the Yangtzé microcontinent, whilst the fauna of western Bac Bo appears to be more closely allied with that of the northern Gondwanaland margin. One new additional chonetoidean genus, Orthochonetes, is described in a note added to the systematic section.