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The extinction event produced major changes in Paleogene insect communities. Many groups of ants were present in the Cretaceous, but in the Eocene ants became dominant and diverse, with larger colonies. Butterflies diversified as well, perhaps to take the place of leaf-eating insects wiped out by the extinction.
The climate across the Cretaceous–Paleogene boundary (K–Pg or formerly the K–T boundary) is very important to geologic time as it marks a catastrophic global extinction event. Numerous theories have been proposed as to why this extinction event happened including an asteroid known as the Chicxulub asteroid, volcanism , or sea level changes.
Luis Walter Alvarez, left, and his son Walter, right, at the K–T Boundary in Gubbio, Italy, 1981. The Alvarez hypothesis posits that the mass extinction of the non-avian dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth.
Summer: A poll of more than 600 paleontologists and other Earth scientists found 24% to support the impact hypothesis of the Cretaceous–Paleogene extinction event, 38% agreed that the impact occurred but was not the true cause of the mass extinction, 26% denied that any impact had occurred and 12% completely denied the occurrence of a mass ...
However, research concludes that this change would have been insufficient to cause the observed level of ammonite extinction. The regression would also have caused climate changes, partly by disrupting winds and ocean currents and partly by reducing the Earth's albedo and therefore increasing global temperatures. [30]
Climate change due to change of ocean circulation patterns. Milankovitch cycles may have also contributed [11] Paleogene: Eocene–Oligocene extinction event: 33.9 Ma: Multiple causes including global cooling, polar glaciation, falling sea levels, and the Popigai impactor [12] Cretaceous: Cretaceous–Paleogene extinction event: 66 Ma
By the time the Cretaceous-Paleogene, or K/Pg, extinction event was over, about three-quarters of species alive at the time of impact had disappeared forever.
Asteroid impacts: one large impact is associated with a mass extinction, that is, the Cretaceous–Paleogene extinction event; there have been many smaller impacts but they are not associated with significant extinctions, [105] or cannot be dated precisely enough.