The Fall of the Dinosaurs: According to the fossil record, the rule of dinosaurs came to an abrupt end ∼65 million years ago, when all nonavian dinosaurs and flying reptiles disappeared. Several possible mechanisms have been suggested for this mass extinction, including a large asteroid impact and major flood volcanism. Schulte et al. (p. 1214 ) review how the occurrence and global distribution of a global iridium-rich deposit and impact ejecta support the hypothesis that a single asteroid impact at Chicxulub, Mexico, triggered the extinction event. Such an impact would have instantly caused devastating shock waves, a large heat pulse, and tsunamis around the globe. Moreover, the release of high quantities of dust, debris, and gases would have resulted in a prolonged cooling of Earth's surface, low light levels, and ocean acidification that would have decimated primary producers including phytoplankton and algae, as well as those species reliant upon them.

The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic geochemical palaeothermometer (TEX₈₆), we present a record of SSTs for the Campanian–Maastrichtian interval (~83–66 Ma) from hemipelagic sediments deposited on the western North Atlantic shelf. Our record reveals that the North Atlantic at 35 °N was relatively warm in the earliest Campanian, with maximum SSTs of ~35 °C, but experienced significant cooling (~7 °C) after this to <~28 °C during the Maastrichtian. The overall stratigraphic trend is remarkably similar to records of high-latitude SSTs and bottom-water temperatures, suggesting that the cooling pattern was global rather than regional and, therefore, driven predominantly by declining atmospheric pCO₂ levels.

A new planktic foraminiferal zonation has been established for the lower Danian, based on some of most expanded and continuous pelagic sections known to date (from Spain, Tunisia and Mexico). This biozonation is considered valid for low and middle latitudes. The maximum stratigraphical distribution of the index‐species approximately coincides in all the studied sections. The index‐species are abundant and easily recognizable. We propose the following biozones and subzones: Guembelitria cretacea Zone and the Hedbergella holmdelensis and Parvularugoglobigerina longiapertura subzones; the Parvularugoglobigerina eugubina Zone, which is subdivided into the Parvularugoglobigerina sabina and Eoglobigerina simplicissima subzones and the Parasubbotina pseudobulloides Zone with the Eoglobigerina trivialis and Subbotina triloculinoides subzones. A biomagnetostratigraphic correlation and calibration of the stratigraphical ranges of these species suggest that the biohorizons used to define the new biozonation are very isochronous, at least in the geographical areas analysed.

Eustoquio Molina, Laia Alegret, Ignacio Arenillas, José A. Arz, Njoud Gallala, José Manuel Grajales-Nishimura, Gustavo Murillo-Muñetón and Dalila Zaghbib-Turki. Episodes 2009;32:84-95. https://doi.org/10.18814/epiiugs/2009/v32i2/002