about 32,000 years

A big meteorite crashed into Earth, changing the climatic conditions so dramatically that dinosaurs could not survive. Ash and gas spewing from volcanoes suffocated many of the dinosaurs. Diseases wiped out entire populations of dinosaurs. Food chain imbalances lead to the starvation of the dinosaurs.

66 million years ago

The entire reason paleontologists make that split is because of a catastrophe that struck 66 million years ago. The geologic break between the two is called the K-Pg boundary, and beaked birds were the only dinosaurs to survive the disaster.

The results of this study, which were based on estimated real global biodiversity, showed that between 628 and 1,078 non-avian dinosaur species were alive at the end of the Cretaceous and underwent sudden extinction after the Cretaceous–Paleogene extinction event.

Together with contemporary observations, it is possible to make informed estimates of the likelihood such events will occur in the future. For example, an extinction-level comet or asteroid impact event before the year 2100 has been estimated at one-in-a-million.

Extinction happens when environmental factors or evolutionary problems cause a species to die out. Humans also cause other species to become extinct by hunting, overharvesting, introducing invasive species to the wild, polluting, and changing wetlands and forests to croplands and urban areas.

We illegally hunt and kill animals. We bring exotic species into habitats. All of these activities take resources and habitats away from plants and animals. Human activity often changes or destroys the habitats that plants and animals need to survive.