Cretaceous–Paleogene extinction event

The Cretaceous–Paleogene extinction event, 66 million years ago, was a sudden mass extinction of three-quarters of the plant and animal species on Earth. With the exception of some ectothermic species such as the sea turtles and crocodilians, no tetrapods weighing more than 25 kilograms survived. The surviving group of dinosaurs were avians, ground and water fowl who radiated into all modern species of bird.

About Cretaceous–Paleogene extinction event in brief

The Cretaceous–Paleogene extinction event, 66 million years ago, was a sudden mass extinction of three-quarters of the plant and animal species on Earth. With the exception of some ectothermic species such as the sea turtles and crocodilians, no tetrapods weighing more than 25 kilograms survived. The extinction event was severe, global, rapid, and selective, eliminating a vast number of species. Based on marine fossils, it is estimated that 75% or more of all species were made extinct. Non-avian dinosaurs, for example, are known from the Maastrichtian of North America, Europe, Asia, Africa, South America, and Antarctica. The surviving group of dinosaurs were avians, ground and water fowl who radiated into all modern species of bird. Other causal or contributing factors to the extinction may have been the Deccan Traps and other volcanic eruptions, climate change, and sea level change. Despite the severity of the event’s severity, there was significant variability in the rate of extinction between and within different clades. No purely herbivorous mammals seem to have survived the event. Rather, surviving mammals and birds fed on insects, which fed on snails, which in turn fed on ground and insectivores, and carrion-eaters, which ate snails in turn. The event appears to have affected all continents at the same time. It is now generally thought that the K–Pg extinction was caused by the impact of a massive comet or asteroid 10 to 15 km wide, 66 million years ago. It also destroyed a myriad of other terrestrial organisms, including some mammals, birds, lizards, insects, plants, and all the pterosaurs.

In October 2019, researchers reported that the event rapidly acidified the oceans, producing ecological collapse and, in this way as well, produced long-lasting effects on the climate, and accordingly was a key reason for the end-Cretaceous mass extinction. The best-known species perished in the K-Pg extinction, the best- known being the non-Avian dinosaurs. But the extinction also provided evolutionary opportunities: In its wake, many groups underwent remarkable adaptive radiation — sudden and prolific divergence into new forms and species within the disrupted and emptied ecological niches, such as horses, whales, bats, and primates. In January 2020, scientists reported new evidence that the extinctionEvent was mostly a result of the meteorite impact and not volcanism. The fact that the extinctions occurred simultaneously provides strong evidence that they were caused by an asteroid. A 2016 drilling project into the Chicxulub peak ring confirmed that the peak ring comprised granite ejected within minutes from deep in the earth, but contained hardly any gypsum, the usual sulfate-containing sea floor rock in the region. The gypsums would have vaporized and dispersed as an aerosol into the atmosphere, causing longer-term effects on climate and food chain. In the oceans,. the extinction killed off plesiosaurs and mosasaurs and devastated teleost fish, sharks, mollusks, and many species of plankton.

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