The transition from the Bartonian to the Priabonian, as traditionally understood, has long been associated with a series of extinctions and originations in several microfossil groups. The planktonic foraminifer genus Morozovelloides and large species of Acarinina suffered a rapid global extinction, as did many radiolarians. Calcareous nannofossils show several assemblage changes including the acme beginning of Cribrocentrum erbae and the lowest and highest occurrences of Chiasmolithus oamaruensis and C. grandis respectively. In shallow water environments, larger foraminifera also show an extinction among large species of Nummulites, as well as the first occurrences of the stratigraphically important genus Spiroclypeus. However, the correlation between shallow and deep water records remains uncertain, as do the mechanisms driving these biotic events. Here we present the results of a new integrated stratigraphical study (calcareous nannofossils, planktonic foraminifera, larger benthic foraminifera, and low-resolution magnetostratigraphy) of the Urtsadzor section in southwestern Armenia which appears to be continuous through this interval. The Urtsadzor section consists of calcareous siltstones rich in micro-and nannofossils, with interbedded limestones containing abundant larger benthic foraminifera. Our new data enable us to correlate larger foraminiferal events with global plankton biostratigraphy, in a section outside of southwest Europe where most previous correlations have been based. At Urtsadzor, the large Nummulites species of N. millecaput-group are present throughout the whole section but decrease in abundance toward the top. The first occurrence of Spiroclypeus, also occurs in the upper part of the section, marking the SBZ 18/19 boundary. These events are associated with the phylogenetic development of the Nummulites fabianii and Heterostegina reticulata lineages. However, the calcareous plankton biostratigraphy indicates the section is well within the Priabonian; within plank

Wade et al., 2011). The larger benthic foraminiferal markers are the LO of Heterostegina reticulata and Pellatispira in the SBZ18 zone (Less and Özcan, 2012). The Eocene sediments of Southern Armenia, represented by the alternation of shallow and deep-water sediments, are rich in various microfossils: planktonic (PF), smaller (SBF) and larger benthic foraminifera (LBF), nannofossils, dinocysts, and rarely, radiolarians that provide direct correlation of planktonic and benthic bioevents and zonations. Recently, foraminifera, nannofossils, and dinocysts were studied from the middle Eocene to the lowermost Oligocene in Landzhar and Urtsalandzh sections, southern Armenia (Shcherbinina et al., 2017;

From 1935 to 1962 Maslov published two monographs and several other papers on the taxonomy of fossil calcareous algae of diverse ages from the large geographical area of the former USSR. Among many other taxa, he described five new genera (Solenophyllum, Palaeophyllum, Mesolithon, Bicorium and Tomilithon, as a subgenus of Parachaetetes Deninger) which he attributed to the Corallinaceae, and the new genus Karpathia, which he included in the Squamariaceae. Type material of these taxa, except for Mesolithon, is housed in the Geological Institute of the Russian Academy of Sciences, Moscow. Re-examination of the genus types from a modern perspective of coralline algal taxonomy shows that Karpathia is a validly published genus of corallinaceans (subfamily Mastophoroideae) to which several Cenozoic fossil species can be assigned. In contrast, the holotype of P. elegans, the type species of Palaeophyllum, cannot be assigned to any subfamily within the Corallinaceae and its preserved features are inadequate for confidently delimiting a separate genus. Solenophyllum is a valid genus in which Palaeozoic representatives of Corallinales formerly attributed to Parachaetetes Deninger can be included. Tomilithon is considered a younger heterotypic synonym of Solenophyllum. The algal nature of the bioclasts in the type of Bicorium is uncertain.

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