Cretaceous–Paleogene extinction event

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 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), with the exception of some ectothermic species such as sea turtles and crocodilians.

Source: Wikipedia — Cretaceous–Paleogene extinction event (CC BY-SA 4.0)