Prehistoric Earth
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.
FAQs on A Brief on Prehistoric Earth
1. What does the term 'Prehistoric Earth' actually refer to?
Prehistoric Earth refers to the vast period of our planet's history before the invention of writing by humans. It covers everything from Earth's formation about 4.5 billion years ago, through the emergence of the first life forms, the age of dinosaurs, and up to the appearance of the first modern humans.
2. What was the environment of the very early Earth like?
The very early Earth was an extreme environment and completely different from today. It was a hot, molten planet with a toxic atmosphere lacking oxygen. Over millions of years, it cooled down, allowing a solid crust to form. Volcanoes released gases that created a primitive atmosphere, and continuous rainfall for millions of years formed the first oceans.
3. What were some of the dominant animals during the prehistoric ages?
While dinosaurs are the most famous, they dominated only during the Mesozoic Era. Before them, the oceans were filled with creatures like trilobites. The prehistoric world also saw giant insects, massive marine reptiles, and eventually, the rise of mammals after the dinosaurs' extinction.
4. How do scientists learn about life on Prehistoric Earth?
Scientists called paleontologists study prehistoric life by examining fossils. Fossils are the preserved remains, imprints, or traces of ancient organisms found in rock layers. By studying fossils, they can figure out what an animal looked like, what it ate, and the environment it lived in.
5. What was the main cause of the extinction of the dinosaurs?
The most widely accepted theory is that a massive asteroid, about 10 kilometers wide, struck the Earth around 66 million years ago. The impact caused catastrophic environmental changes, including giant tsunamis and a dust cloud that blocked the sun, leading to the collapse of food chains and the extinction of dinosaurs and many other species.
6. Did early humans and dinosaurs live at the same time?
No, this is a common misconception. The last dinosaurs died out about 66 million years ago. The earliest human ancestors, on the other hand, appeared only a few million years ago. There is a time gap of more than 60 million years separating dinosaurs and humans.
7. How was the plant life of prehistoric times different from today?
Prehistoric plant life was very different. The earliest land plants were simple, like mosses and ferns. During the age of dinosaurs, huge forests of non-flowering plants like conifers, cycads, and ginkgoes were common. Flowering plants, which are dominant across the world today, only evolved and became widespread towards the end of the dinosaurs' reign.
8. Why is it important to study the history of Prehistoric Earth?
Studying Prehistoric Earth helps us understand several key concepts today. Here’s why it's important:
- It shows us how life has evolved and adapted over billions of years.
- Studying past mass extinctions can provide lessons on the fragility of ecosystems.
- Analysing ancient climates helps scientists create better models for understanding modern climate change.
