The World Before Humans Reigned

“Fossils form when an animal dies in water, then is covered by layers of mud and sediment. Over time, more and more layers will form on top and other dead organisms will fossilize as well. The amount of layers corresponds to the age of the rock. Usually the oldest fossils are toward the bottom with the newest fossils at the top.”

— Maiya

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The world before humans reigned.

The Mesozoic Era The big bang is the idea that the universe was suddenly born. This idea contradicts with what scientists previously thought, that the earth was endless and infinite. About 4 billion years ago, in a hot dense environment, the earth was created. The first living things were microorganisms, later named prokaryotes. It was then, in the Mesozoic Era 245 and 66 million years ago, where non-bird dinosaurs lived (Kurzgesagt In a Nutshell, 2014). This era was divided into three different ones: Triassic, Jurassic and Cretaceous. At the time, all the continents were connected in a landmass called Pangea (Natural History Museum). The climate was hot and it was made mostly of deserts. Dinosaurs could live in this climate because they were reptiles who adapted to surviving in this type of weather. Their kidneys were better at storing water and their skin was less porous (Natural History Museum). This gave them the advantage of losing less water. In the Jurassic period, Pangea split, creating two different lands: Laurasia and Gondwana. Scientists learned about this because of fossil records showing the same dinosaurs in two different places on earth. Over time, the characteristics of each part of land changed causing it to be cooler in some areas, seas started to rise, rainfall, forests were growing as well as plants and vegetation. In this time, more than 43 different species have adapted to different climates and needs. In the last years of the Mesozoic Era, the cretaceous period, continents were separating and a more diverse species of dinosaurs was forming.

The K-T extinction Sixty-six million years ago, the 180 million year period, reigned by dinosaurs, ended. An asteroid that ranged any size from tens to hundreds of meters in diameter crashed into the earth, killing most dinosaurs. The result of this was debris and a dust-filled sky, reducing the amount of light that plants needed to receive in order to continue growing. Herbivores that relied on plants died because they were no longer around, then carnivores had no meat to eat so they did as well. The damage that this did was not only to the dinosaurs- today, we can still see the Chicxulub crater, located in Mexico. Not all species died during this event. It is believed that dinosaurs that could fly have survived and are still around today. Scientists also believe that all crocodilians and reptiles have some relation to dinosaurs through comparative anatomy. Scientists also believe that fish survived the KT extinction and have evolved from fish.

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KARSTEN SCHNEIDER / Getty Images In this image, you can see the meteorites coming down towards earth killing all dinosaurs.

Finding dinosaurs through fossils Fossils are made when an animal dies in water, then is covered by layers of mud and sediment. Over time, more and more layers form on top and other dead organisms will fossilize as well. The amount of layers corresponds to the age of the rock. Usually, the oldest fossils are towards the bottom and the newest at the top. In the centre of London 170 years ago, the first “complete” skeleton of a dinosaur was unearthed. In the 17th century, before geology and palaeontology existed as science, scientists did not want to believe that fossils were the remains of long-dead organisms. As BBC said towards the dinosaurs they found, “All three animals were similar to one another and different from every other animal” Fossils showed us how life was before humans reigned and the différences in life. We also learnt about extinct animals.

Citations:

“How Are Fossils Formed?” ​The Australian Museum​, australianmuseum.net.au/learn/australia-over-time/fossils/how-are-fossils-formed/.

The Editors of Encyclopaedia Britannica. “K–T Extinction.” ​Encyclopædia Britannica​, Encyclopædia Britannica, Inc., 21 May 2020, www.britannica.com/science/K-T-extinction.

Barras, Colin. “Earth - Dinosaurs Were Discovered by British Scientists.” ​BBC​, BBC, 3 June 2015, www.bbc.com/earth/story/20150603-the-land-that-gave-us-dinosaurs.

“When Did Dinosaurs Live?” ​Natural History Museum​, www.nhm.ac.uk/discover/when-did-dinosaurs-live.html.