[Biology Class Notes] on A Brief on Prehistoric Earth Pdf

4.54 billion years ago, the earth had formed, and the prehistoric maps of earth were entirely different from how we see it today. 

It was a very uninhabitable place with hellish temperatures hot enough to boil water. The atmosphere was lacking oxygen, and the land was a barren wasteland without any life. Oceans were practically non-existent as all of the water was trapped in the form of gases.

About 3.8 billion years, the earth cooled down enough for these gases to start precipitating as rain. It rained for millions of years, eventually filling the vast basins and gorges, originating the very first water bodies.

Even though it rained, the oceans remained empty for a while – with the very first signs of life emerging almost after 540 million years later. The very first organism on earth may have been unicellular, something similar to a bacteria, and sharing the similarity with its cell structure as well. These prehistoric animals still on earth have evolved a lot over the years.

From this group of bacteria-like unicellular organisms, life would go on to diversify and speciate into a multitude of different species. However, with time some of these organisms would go extinct, and the niches they left were eventually replaced with other organisms. This cycle manifested itself over millions of years, originating an increasingly complex plethora of creatures.

One of the most eminent groups of organisms that rule the prehistoric earth maps were the reptiles; the dinosaurs. Their shape and size varied greatly, with the tiniest one being no bigger than a chicken and the biggest one weighing over 77 tons. For millions of years, Dinosaurs roamed the earth until an asteroid hit the earth, besides that the change in climate also brought about their extinction. However, technically speaking not all dinosaurs went extinct – the birds that we see today are the scions of dinosaurs. They furcated off from theropods, a family of dinosaurs, which were characteristically bipedal. This prehistoric life on earth is evident as all modern birds are bipedal.

The next evolutionary milestone is the rise of the Great apes, which ultimately furcated off into modern humans. However, evolution has not stopped here, even in today’s world humans are rapidly evolving and adapting to change. Though the changes are not quite perceptible, scientists theorize that an entirely new species of humans could arise over the next few millennia.