Palaeobiodiversity and Palaeoenvironments, 2026 (SCI-Expanded, Scopus)
A Middle Devonian ostracod fauna is described from dark-grey limestones and grey shales of the Tsagaankhaalga Formation in southern Mongolia. Conodonts from these deposits range from the Polygnathus partitus to costatus zones, representing the Eifelian Choteč Event levels. The fauna is characterised by low diversity and high quantity of specimens. Eleven genera and fourteen ostracod species have been recognised belonging to the orders Palaeocopida, Platycopida and Podocopida. The palaecopin, platycopin and podocopin ostracod assemblage can be characterised as an Eifelian Mega-Assemblage (II-III), which lived in open shallow-marine environment. The Mongolian Eifelian ostracod fauna includes endemic and cosmopolitan species. The studied fauna is most closely related to coeval faunas of Laurussia and Siberia.