ABSTRACT The uppermost Famennian (Upper Devonian) is marked by the reappearance of trilobites following their almost complete disappearance at the end of the Frasnian. Among these trilobites, the latest Famennian phacopids represented by Omegops are recorded and illustrated from the carbonate succession of the Arshakiaghbyur Horizon in the Armash section (Ararat Province), located 70 km southeast of the capital, Yerevan. Although the assemblage displays a low taxonomic diversity, it includes a newly identified species, Omegops armeniensis . The age of the fossil-bearing interval is constrained by the presence of the conodont species Icriodus raymondi in the lower part of the studied section and of Polygnathus inornatus and Siphonodella praesulcata in the upper part of it, indicating a time span from the Middle expansa to praesulcata zones. These trilobites represent the youngest known phacopids and are among the victims of the Hangenberg Crisis that took place near the Devonian–Carboniferous boundary. The Armenian phacopid fauna formed a trilobite association inhabiting a shallow shelf together with diverse brachiopod and coral communities. At a global scale, this occurrence is in agreement with the interpretation of a shallow and near-shore marine habitat for Omegops species during the latest Famennian.
Crônier et al. (Wed,) studied this question.