23 Facts From Earth’s Violent History in Chronology

The 3.6 million-year-old Laetoli footprints, one of the most important finds concerning human evolution and evidence of upright bipedal walking, was discovered by Paleoanthropologist Andrew Hill when he dove into the ground during the middle of an elephant dung fight with a colleague.

A mere 12,000 years ago a species (Homo floresiensis) closely related to modern humans had been living on an Indonesian island. They used fire and rather advanced tools, yet were only about 3 feet tall, weighing around 25kg.

During the late Jurassic and Cretaceous periods, the majority of the oceans reefs weren't built by corrals, but rather a group of bivalve clam like mollusks called Rudists.

20 million years ago in North America, the spread of ancient cats led to the extinction of many dog species. There used to about 30 canine species in North America. Only 8 remain.

In the last 5 millennia, genetic change in humans has occurred at a rate roughly 100 times higher than any other period of human evolution. Humans today are more genetically different from humans living 5,000 years ago than these people were from humans living 40,000 years ago.

49 million years ago, a giant bloom of floating plants (Azolla) in the Arctic Ocean tipped the Earth's climate from very hot to very cold.

Blond hair in humans developed only 11,000 years ago as an evolutionary response to the lack of sunlight in Northern Europe to enable more Vitamin-D synthesis.

Pangaea was not the first supercontinent. That honor goes to the billion-year-old landmass known as Rodinia. The continents routinely split apart and come back together in a process known as the supercontinent cycle.

Around 70,000 years ago the Volcano Toba in Indonesia erupted and covered the earth with so much ash the sun was dimmed for 6 years. The population of early humans neared extinction and some studies indicate there were as few as 40 breeding pairs.

The Cambrian Explosion might be explained by rising sea levels 540 million years ago which resulted in three times as much calcium being dissolved into the sea. Life forms had to create shells, bones and other hard tissues in response leading to the diversity of life we see today.