Before this, all life had been single-celled, and so relatively simple. No one knows why this happened. The Cambrian Explosion, of diversity of species of life. The fossil record gets much richer, beginning in rocks this old. No one knows why.
Dinosaurs become extinct, thought to be because of a giant meteorite impact on Earth.
Whether the imapct was from an asteroid or comet, or single or multiple impacts, is under debate. It was essentially an ape that walked upright. Their fossils and tools have been found from Africa to China to Java. Although conventional wisdom decrees they originated in Africa, current evidence cannot rule out Asia. All living humans are descended from one woman, at about this time, who probably lived in South Africa, as shown by tracing samples of DNA, taken from people all over the world.