Late Ordovician and early Silurian brachiopods from the Zagros Ranges, Iran

Mohammad Ghavidel-Syooki1,*, Leonid E. Popov2,*,
Mansoureh Ghobadi Pour3, J. Javier A ´ lvaro4 and Mohammad H. Ehsani1
1Institute of Petroleum Engineering, Technical Faculty of Tehran University, P.O. Box 11365-4563, Tehran, Iran

2Department of Geology, National Museum Cardiff, Cathays Park, Cardiff CF10 3NP, Wales, UK

3Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran

4Centre of Astrobiology (CSIC/INTA), Ctra. de Torrejo´n a Ajalvir km 4, 28850 Torrejo´n de Ardoz, Spain

*Corresponding authors
ABSTRACT: Brachiopods are among the most common components of the Late Ordovician
benthic faunal assemblages recorded in the Faraghan Mountains, Zagros Ranges, Iran. A total
of 19 species referable to 16 genera are identified, including seven new species; namely Drabovia
elegans, Hibernodonta bonehensis, Hedstroemina zakeenensis, Jezercia faraghani, Protomendacella
multicostata, Tafilaltia dargazensis and Tafilaltia seyahouensis. Reported brachiopod assemblages
are oligotaxic (2–3 species per assemblage) to monotaxic. The only exception is the medium diversity
Aegiromena-Hedstroemina Association, with up to ten species, which occurs at the lower part of
the A. nigerica Zone. Low diversity patterns were probably controlled by the palaeogeographical
position of the region in high southern latitudes throughout the Ordovician. Paterula sp. and Iranospirifer
sp. are the only brachiopods documented from the Silurian (Llandovery) Sarchahan Formation.
This paper gives the first detailed report of shelly fossils from the Llandovery ‘hot shale’ of the
Arabian margin of Gondwana. Most of the Katian genera, and many of their species, are shared
with neighbouring high- to mid-latitude peri-Gondwanan margins, including Morocco, Spain,
France, Sardinia and Bohemia.
KEY WORDS: biofacies, biogeography, Faraghan Mountains, Gondwana, Katian, Llandovery