Living things that lived long ago and went extinct look like they came out of fantasy movies compared to today’s creatures. But to what did they owe their gigantic size?
First dinosaurs We are very, very small compared to prehistoric creatures. Besides dinosaurs, snakes, felines, and more remain a beast compared to their counterparts today.
Besides plants and insects reached unimaginable proportions. Then something happened and living things got smaller. So what was it that caused this huge impact?
The main reason why prehistoric life forms were so large was “oxygen produced by cyanobacteria”.
Visible as a blue-green layer over lakes and seas, these microscopic organisms were able to obtain their energy through photosynthesis 2.4 billion years ago. Thanks to their photosynthesis with carbon dioxide, oxygen – waste for them – was released into the atmosphere and life forms on Earth changed drastically. The emergence of oxygen in the atmosphere “The Great Oxidation Event” is called.
Oxygen-breathing organisms become more active and larger.
The amount of oxygen increased 800 million years ago, and further increased 500 million years ago. This excess of oxygen It was an invaluable blessing for living things to grow. Living things, whose cells were filled with oxygen, became more agile and larger over time.
Then a mass extinction occurred due to the meteorite impact, and Oxygen levels dropped drastically. Only tiny creatures that could survive on less oxygen survived this disaster.
According to Cope’s Rule, living things will be big again many years from now.
According to this idea, living things as we evolve over time shows a growth trend. Prehistoric creatures also reached gigantic sizes over time. 66 million years have passed since the extinction of these creatures, and this period is very short for living things to reach gigantic proportions again.
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Oxygen may not be the only reason!
In those times the land masses were larger, which means more space means. It is known that creatures that evolved in a limited area, especially on islands, were smaller in size. Pygmies and aborigines from the island peoples are the best examples of this.
Sources: 1, 2, 3, 4, 5, 6
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