Timeline of the Earth As stated in “The Big Bang Theory” theme song, our universe as we know it started because of one big explosion. This explosion was caused by a supernova 13.7 billion years ago. When the big bang happened, all of the elements that were in the star were expelled outward. Around .4 billion years after the big bang, first generation stars started to form, these are the stars that created most of our elements.They were made of period two, three, and four elements. Like every star, these stars ran out of energy and exploded making new elements that are found on our periodic table. They created period four, five, six, and seven elements. 4.6 billion years ago a protoplanetary disc was created. Around this the elements started …show more content…
Then around 3.5 billion years ago, living cells with DNA were created. They formed for more than three billions years before the Cambrian period which was 540 million years ago. This is when the first creatures such as trilobites came to be. After this was the Silurian period where the first land plants, cooksonia, grew, and the first fish, haikouichthys, swam. After this came the Devonian period which was 416 million years ago. The cephalaspis swam in freshwater and evolved so it could swim in water and walk on land. Two million year later, 2.5 million years ago, was the very well known Triassic period. This is when the earliest dinosaurs roamed the Earth. This is also when the first mammals were being born and evolving. Meanwhile tectonic plates were pushing land masses away from each other and split up Pangea and brings us into the Jurassic period. Throughout the Cretaceous period, the continents were being pushed further apart and the first dinosaurs walked on two legs. This all ended when a meteor hit the Earth and all the dinosaurs went extinct. 49 million years ago, the first primates were swinging in the trees and eventually walking on the ground. These evolved into who we are now. It is amazing how we came from one huge explosion, and how we have created more than those dinosaurs could have ever