[1] Measurements of the calcium isotopic composition (dCa) of planktonic foraminifera from the western equatorial Pacific and the Indian sector of the Southern Ocean show variations of about 0.6% over the past 24 Myr. The stacked dCa record of Globigerinoides trilobus and Globigerina bulloides indicates a minimum in dCasw (seawater calcium) at 15 to 16 Ma and a subsequent general increase towar...

Sea surface reservoir ages must be known to establish a common chronological framework for marine, continental, and cryospheric paleoproxies, and are crucial for understanding ocean-continent climatic relationships and the paleoventilation of the ocean. Radiocarbon dates of planktonic foraminifera and tephra contemporaneously deposited over Mediterranean marine and terrestrial regions reveal th...

Birth-death models are central to much macroevolutionary theory. The fundamental parameters of these models concern durations. Different species concepts realize different species durations because they represent different ideas of what birth (speciation) and death (extinction) mean. Here, we use Cenozoic macroperforate planktonic foraminifera as a case study to ask: what are the dynamical cons...

We present a detailed history of glacial to Holocene radiocarbon in the deep western North Atlantic from deep-sea corals and paired benthic-planktonic foraminifera. The deglaciation is marked by switches between radiocarbon-enriched and -depleted waters, leading to large radiocarbon gradients in the water column. These changes played an important role in modulating atmospheric radiocarbon. The ...

[1] The North Atlantic and Norwegian Sea are prominent sinks of atmospheric CO2 today, but their roles in the past remain poorly constrained. In this study, we attempt to use B/Ca and dB ratios in the planktonic foraminifera Neogloboquadrina pachyderma (sinistral variety) to reconstruct subsurface water pH and pCO2 changes in the polar North Atlantic during the last deglaciation. Comparison of ...

[1] The stable boron isotope composition (dB) of fossil foraminiferal shells is used as a paleo-pH recorder and is therefore one of the most promising paleocarbonate chemistry proxies (‘‘paleoacidimetry’’). One crucial question regarding this proxy is whether foraminifera record the pH of the bulk seawater or the pH of the microenvironment (diffusive boundary layer, 500 mm), which is strongly i...

Birth–death models are central to much macroevolutionary theory. The fundamental parameters of these models concern durations. Different species concepts realize different species durations because they represent different ideas of what birth (speciation) and death (extinction) mean. Here, we use Cenozoic macroperforate planktonic foraminifera as a case study to ask: what are the dynamical cons...

in this study biostratigraphy of the upper cretaceous deposits (gurpi formation) in sepidan section located in the interior fars basin (sw iran) was studied. the gurpi formation in this section consists of 360 m lime shale, argillaceous limestone and shale laid continuously on the ilam formation and with a paraconformity under the pabdeh formation. nine genera and 27 species of planktonic foram...

The taxonomy and phylogeny of the Miocene to Recent genus Sphaeroidinellopsis have been documented in previous studies, but evolution this lineage remains unclear. Some authors debated past, choosing a variety parameters discriminate morphospecies. Here we present new scanning electron microscope analyses specimens from Ocean Drilling Program (ODP) Site 925 (Ceara Rise, western equatorial Atlan...