Planktic foraminifera are an abundant component of deep-sea sediment and are critical to geohistorical research, primarily because as a biological and geochemical system they are sensitive to coupled bio-hydro-lithosphere interactions. They are also well sampled and studied throughout their evolutionary history. Here, we combine a synoptic global compilation of planktic foraminifera with a stochastic null model of taxonomic turnover to identify statistically significant increases in macroevolutionary rates. There are three taxonomic diversifications and two distinct extinctions in the history of the group. The well-known Cretaceous-Paleogene extinction is of unprecedented magnitude and abruptness and is linked to rapid environmental perturbations associated with bolide impact. The Eocene-Oligocene boundary extinction occurs due to a combination of factors related to a major reorganization of the global climate system. Changes in ocean stratification, seawater chemistry, and global climate recur as primary determinants of both macroevolutionary turnover in planktic foraminifera and spatiotemporal patterns of deep-sea sedimentation over the past 130 Myr.

Understanding the links between long-term biological evolution, the ocean-atmosphere system and plate tectonics is a central goal of Earth science. Although environmental perturbations of many different kinds are known to have affected long-term biological evolution, particularly during major mass extinction events, the relative importance of physical environmental factors versus biological interactions in governing rates of extinction and origination through geological time remains unknown. Here we use macrostratigraphic data from the Atlantic Ocean basin to show that changes in global species diversity and rates of extinction among planktonic foraminifera have been linked to tectonically and climatically forced changes in ocean circulation and chemistry from the Jurassic period to the present. Transient environmental perturbations, such as those that occurred after the asteroid impact at the end of the Cretaceous period approximately 66 million years ago, and the Eocene/Oligocene greenhouse-icehouse transition approximately 34 million years ago, are superimposed on this general long-term relationship. Rates of species origination, by contrast, are not correlated with corresponding macrostratigraphic quantities, indicating that physiochemical changes in the ocean-atmosphere system affect evolution principally by driving the synchronous extinction of lineages that originated owing to more protracted and complex interactions between biological and environmental factors.

[1] Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m 2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to <0.07 W/m 2 at distances >15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m 2 , a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present-day volcanism is confined to the region with the highest heat flow.

Severe climatic and environmental changes are far more prevalent in Earth history than major extinction events, and the relationship between environmental change and extinction severity has important implications for the outcome of the ongoing anthropogenic extinction event. The response of mineralized marine plankton to environmental change offers an interesting contrast to the overall record of marine biota, which is dominated by benthic invertebrates. Here, we summarize changes in the species diversity of planktic foraminifera and calcareous nannoplankton over the Mesozoic-Cenozoic and that of radiolarians and diatoms over the Cenozoic. We find that, aside from the Triassic-Jurassic and Cretaceous-Paleogene mass extinction events, extinction in the plankton is decoupled from that in the benthos. Extinction in the plankton appears to be driven primarily by major climatic shifts affecting water column stratification, temperature, and, perhaps, chemistry. Changes that strongly affect the benthos, like acidification and anoxia, have little effect on the plankton, or are associated with radiation.