The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the die-off of the dinosaurs and other species that took place some 65.5 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs' food supply.
Homo erectus were the first of the hominins to emigrate from Africa, and, from 1.8 to 1.3 million years ago, this species spread through Africa, Asia, and Europe. One population of H. erectus, also sometimes classified as a separate species Homo ergaster, remained in Africa and evolved into Homo sapiens.