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The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (K–Pg boundary), slightly more than 66 million years ago. [ 7 ] The crater is estimated to be over 150 km (93 mi) in diameter [ 10 ] and 20 km (12 mi) in depth, well into the continental crust of the region of about 10–30 km (6.2–18.6 mi) depth.
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.
The Cretaceous–Paleogene (K–Pg) extinction event, [a] also known as the K–T extinction, [b] was the mass extinction of three-quarters of the plant and animal species on Earth [2] [3] approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs.
Walter Alvarez at the original site where he discovered the dinosaur extinction evidence near Gubbio, Italy. Alvarez and his father Luis W. Alvarez, together with Frank Asaro and Helen Michel, discovered that a clay layer occurring right at the Cretaceous–Paleogene (K-Pg) boundary was highly enriched in the element iridium.
The paper announcing the discovery of the feature was published in Science Advances in 2022, [1] with an impact origin being confirmed in 2024. The crater is around 9.2 km (5.7 mi) in diameter, and formed around , close to the Cretaceous–Paleogene boundary when a small asteroid struck the ocean floor. [2]
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out, widely thought to have been caused by the impact of a large asteroid that formed the Chicxulub crater in the Gulf of Mexico.
Cretaceous-Paleogene boundary [ edit ] Because the Raton Formation is a well-preserved sequence of rocks spanning the Cretaceous-Paleogene boundary , it has been studied for evidence of a large meteor impact at the end of the Cretaceous that is thought to have caused the Cretaceous–Paleogene extinction event .
The Cretaceous–Paleogene extinction event was a large-scale mass extinction of animal and plant species in a geologically short period of time, approximately (Ma). It is widely known as the K–T extinction event and is associated with a geological signature, usually a thin band dated to that time and found in various parts of the world ...