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The Aras Valley section (NW Iran) exposes a sedimentary succession that
allows to study ostracod diversity patterns during/across the end-Permian
mass extinction because of its ubiquitous fossil record. For the present
study, 59 samples were investigated for their ostracod abundances, which
ranged from 4 to 31500 specimens per 500 g. In 45 sample horizons, the
ostracods were identified to the species-level. In total, 3,425 specimens
were determined and 62 species were identified, of which one genus and ten
species are described for the first time: Fabalicypris veronicae Gliwa,
sp. nov., Orthobairdia capuliformis Gliwa, sp. nov., Araxobairdia formosa
Gliwa, gen. et sp. nov., Bairdiacypris kathleenae Gliwa, sp. nov.,
Eumiraculum mettei Gliwa, sp. nov., Liuzhinia julfensis Gliwa, sp. nov.,
Carinaknightina hofmanni Gliwa, sp. nov., Cavellina fosteri Gliwa, sp.
nov., Cavellina hairapetiani Gliwa, sp. nov. and Hungaroleberis striatus
Forel, sp. nov. The assemblages show, at the end-Permian mass extinction
event, a complete turnover from a low-diversity Fabalicypris-dominated
pre-extinction community to a more diverse Bairdiacypris-dominated
post-extinction community. The turnover coincides with the significant
temperature increase that was previously recorded from NW Iranian
sections. The low diversity in the horizon immediately below the
extinction horizon indicates that environmental changes, such as thermal
stress, may have had an impact on the ostracod assemblages prior to the
extinction event. In comparison with other diverse ostracod assemblages
from the Palaeotethyan realm, the ostracods of the Aras Valley section are
not associated with microbialites.
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