Question

Approximately when did the mass extinction of dinosaurs occur?

Answer 1

About 66 million years ago

Step-by-step explanation:

Geological evidence indicates that dinosaurs became extinct at the boundary between the Cretaceous and Paleogene eras, about 66 million years ago, at a time when there was worldwide environmental change resulting from the impact of a large celestial object with the Earth and/or from vast volcanic eruptions.

Answer 2

65 Million Years ago or around that, after living on Earth for about 165 million years.