Early to Middle Ordovician lingulate brachiopods from the Lashkarak Formation, Eastern Alborz Mountains, Iran

Abstract

Popov, L.E., Ghobadi Pour, M. & Hosseini, M., March, 2008. Early to Middle Ordovician lingulate brachiopods from the Lashkarak Formation, Eastern Alborz Mountains, Iran. Alcheringa 32, 1–35. ISSN 0311-5518.

Low- to moderate-diversity faunas of lingulate brachiopods are reported for the first time from the Lower to Middle Ordovician Lashkarak Formation of the Eastern Alborz Mountains in northern Iran. Twenty-three species of 20 genera referable to four successive lingulate brachiopod assemblages are systematically described, including Aipyotreta conferta sp. nov., Ghavidelia damghanensis gen. et sp. nov. and Thysanotos multispinulosus sp. nov. The occurrence of Alichovia and Acrotreta, and the early appearance of Biernatia suggest Baltic affinities of the fauna, but scaphelasmatids and Myotreta are missing in the Iranian section. The opportunistic Thysanotos – Leptembolon Association appears in Eastern Alborz in the lower Floian prior to the onset of the carbonate sedimentation.

Key words:

• Ordovician
• Iran
• Brachiopoda
• Lingulata
• systematics
• biogeography

Acknowledgements

We thank Dr Glen A. Brock (Macquarie University) and Prof. Lars E. Holmer (Uppsala University) for constructive critical comments on the manuscript. Leonid Popov acknowledges support from the National Museum of Wales. Mansoureh Ghobadi Pour acknowledges her visit to the National Museum of Wales, Cardiff with financial support from the Iranian Student Scholarship. Fieldwork and research in Iran were supported by the Sylvester-Bradley Award from the Palaeontological Association. We are grateful to Dr Vachik Hairapetian (Azad University, Esfahan) for assistance in the field and laboratory work, and to Dr Oliver Lehnert (University of Erlangen) for identification of conodonts.