geologia: Timeline of Cretaceous–Paleogene extinction event research

Evidence: 57 • authority: 72

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. Prior to 2013, it was commonly cited as having happened about 65 million years ago, but Renne and colleagues (2013) gave an updated value of 66 million years. Evidence indicates that the asteroid fell in the Yucatán Peninsula, at Chicxulub, Mexico. The hypothesis is named after the father-and-son team of scientists Luis and Walter Alvarez, who first suggested it in 1980. Shortly afterwards, and independently, the same was suggested by Dutch paleontologist Jan Smit. In March 2…

Evidence: 45 • authority: 72

The Cretaceous–Paleogene (K–Pg) extinction event, formerly known as the Cretaceous–Tertiary (K–T) extinction event, was a major mass extinction of three-quarters (75%) of the plant and animal species on Earth which occurred around 66 million years ago. The event caused the extinction of all the non-avian dinosaurs and most other tetrapods weighing more than 25 kg (55 lb), excepting some ectothermic species such as sea turtles and crocodilians. It marked the ends of both the Cretaceous period and the Mesozoic era, and logged the beginning of the current geological era, the Cenozoic era. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary or K…

Evidence: 36 • authority: 72

Evidence: 30 • authority: 80

Evidence: 29 • authority: 72

The term iridium anomaly commonly refers to an unusual abundance of the chemical element iridium in a layer of rock strata at the Cretaceous–Paleogene (K–Pg) boundary. The unusually high concentration of a rare metal like iridium is often taken as evidence for an extraterrestrial impact event.

Evidence: 24 • authority: 88

Evidence: 24 • authority: 92

Application of a novel schema for describing fossil fern foliage and investigating taxonomic and morphological change across the Cretaceous-Paleogene boundary in western North America.. Premise The Chicxulub asteroid impact at the Cretaceous-Paleogene (K-Pg) boundary triggered a mass extinction 66 million years ago. Ferns thrived in the aftermath of the extinction, evidenced by the well-documented "fern spore spike." However, fern macrofossil records across the K-Pg boundary are less understood. Methods We analyzed 698 fern macrofossils from 19 Cretaceous and 83 Paleogene localities in the Raton (Colorado and New Mexico), Denver (Colorado), and Williston basins (North Dakota and Montana), g…

Evidence: — • authority: 65