Paleoecological inferences for turborotalita nikolasi (koutsoukos, 2014) based on stable carbon and oxygen isotopes

The species Turborotalita nikolasi first appeared immediately after the Cretaceous-Paleogene (K-Pg) boundary and is considered the progenitor of all Cenozoic normal perforate species. We present delta O-18 and delta C-13 isotope signals of T. nikolasi specimens and compare them with those of mixed -layer (Guembelina cretacea), thermocline (Subbotina trivialis and Chiloguembelina midwayensis), and deep water (Nuttalides truempyi) species with glassy shell preservation from Sao Paulo Plateau [Deep Sea Drilling Project (DSDP) Site 356]. Turborotalita nikolasi delta O-18 values are similar to those of G. cretacea, suggesting that both species cohabited the mixed layer. Values of delta C-13 for T. nikolasi are higher than those of all other planktic foraminiferal species, which may have been due to the presence of photosymbionts, and thus might repre-sent the earliest known record of photosymbiosis for Cenozoic planktic foraminifera. Nuttalides truempyi d(13)C values are re-markably high at Site 356, indicating low C-12 abundance in deep waters, which could be related to reduced inefficiency of the biological pump in transporting C-12 to the bottom of the ocean after the K-Pg boundary during the first similar to 300 kyr of the Danian.