Warum verschwanden die Dinosaurier? Das Kreide/Paläogen-Ereignis chemisch-physikalisch betrachtet

The massive extinction event at the end of the Cretaceous period owes its popularity largely to the demise of the (non-avian) dinosaurs. However, many other life forms disappeared at the same time. For a long time, the reasons for this event remained shrouded in extensive and sometimes in hindsight dilettantish speculations. Only after a multidisciplinary team of researchers had identified a significant enrichment of the element iridium (and other platinum group elements) in the boundary layer between the Cretaceous and the Paleogene period, a plethora of examinations was unleashed to confirm or falsify their asteroid impact hypothesis. After 45 years of research, chemical, physical and geological evidence appears to strongly support the assumption of the impact of an asteroid of more than 10 km in diameter. Large quantities of produced sooth and released carbon dioxide, sulphate aerosols, and ejecta, together with global wildfires, earthquakes and mega-tsunamis triggered a massive but short-lived climate change, beginning with a significant cooling and global darkening. Preceding massive volcanism and regressing ocean levels may have had already weakened global ecosystems before the impact. Without this extinction event, originating from a particularly unlucky (and in principle unlikely) combination of circumstances, also with respect to the geochemical conditions of the impact location, the rise of mammals, leading also to the species homo sapiens and its ancestors would most likely have never occurred.