Punctate Devonian and Early Carboniferous Rhynchonellids (Brachiopoda) of Transcaucasia

The diversity of the Late Devonian and Early Carboniferous punctate rhynchonellids of Transcaucasia is revised, and various possible reasons for the origin of punctation are considered. It appeared in different superfamilies of the order Rhynchonellida as a result of adaptation to the oxygen depletion towards the sea bottom. The first punctate rhynchonellids appeared in Transcaucasia after the Frasnian-Famennian ecosystem crisis. These are Greira transcaucasica Erlanger, 1993 and Sharovaella mirabilis Pakhnevich, 2012, found in the sediments of the Cyrtospirifer asiaticus-Mesoplica meisteri Zone of the Lower Famennian. Most of the punctate rhynchonellids settled along the northern coast of Gondwana. Only species of the genus Araratella Abramian, Plodowski and Sartenaer, 1975 are known to have inhabited the seas along the southern coast of Laurussia. Of the Transcaucasian species, only Tchanakhtchirostrum araraticum (Abramian, 1957) continued to exist into the Early Carboniferous, but soon became extinct.