A new evidence of passing the Maastichtian–Paleocene boundary by larger benthic foraminifers: The case of Elazigina from the Maastrichtian Tarbur Formation of Iran

We describe a new Maastrichtian species of the benthic foraminifer Elazigina siderea from Tarbur Formation. Its main characters are the presence of heavy feathered umbilical sutures, a wide umbilical plug, and umbilical piles. This species, formerly reported from Turkey as Smoutina cruysi, constitutes the oldest known record of the genus Elazigina. Elazigina siderea sp. nov. comes from the Arabian domain and its presence is probably related to the migration of the Cretaceous foraminifer Orbitokathina. Prior to this study, the oldest representatives of this genus were only known from the Paleocene. Therefore, the presence of the new taxon in the Maastrichtian suggests the genus Elazigina passed the Cretaceous–Paleogene boundary, and survived to the environmental crisis associated with a great biosphere mass extinction that wiped out most of the Late Cretaceous larger foraminifers. This is supported by shell features displayed by Elazigina siderea sp. nov., interpreted as adaptation to thrive under elevated trophic levels, like the species of another benthic foraminifer Laffitteina.