Early Ordovician organophosphatic brachiopods with Baltoscandian affinities from the Alay Range, southern Kyrgyzstan

Abstract

Organophosphatic-shelled brachiopods (Subphylum Linguliformea, Class Lingulata) of early Ordovician (Arenig) age are described for the first time from carbonate olistoliths within the Silurian Pulgon Formation of the Kichik Alay Range, southern Kyrgyzstan. The assemblages include Paterula? naukatensis sp. nov., Rowellella sp., Orbithele ceratopygarum (Br⊘gger), Acrotreta korynevskii Holmer & Popov, Ombergia mirabilis gen. et sp. nov., Eoconulus cf.primus Popov & Holmer, and Palaeoglossa? aff. razumovskii (Lermontova). The Kyrgyzstanian faunas appear to correlate mainly with assemblages from the upper Hunnebergian or lower Billingenian regional stages of Baltoscandia. Taxa in common with those from the early Arenig of Baltoscandia and the South Urals include O. ceratopygarum and A. korynevskii. Ombergia mirabilis is known otherwise only from coeval strata in Baltoscandia. It is probable that the Kyrgyzstanian olistoliths originated from early Ordovician intra-oceanic volcanic island arcs in the proximity of Gondwana, and the microbrachiopod faunas around these islands may have given rise to the more widespread and richer faunas that spread across Baltica during the rest of the Ordovician, as the island complexes drifted towards Baltica.

Key Words:

• Brachiopoda
• Linguliformea
• Lingulata
• taxonomy
• early Ordovician
• Arenig
• Kyrgyzstan
• Baltica