Why were animals so much bigger in prehistoric times?

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Dinosaurs seemed to have generally been so much larger than animals today. Huge dragonflies that dwarf their modern counterparts, turtles 10ft long. What is the mechanism that allowed them to be so large, or conversely makes modern ones smaller? Is it about Oxygen levels, or efficiency, or something else?

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Anonymous 0 Comments

Higher concentration of oxygen in the air. That’s really it. That being said the blue whale is the largest known animal of any sort to ever exist but obviously marine animals have differences than land mammals. In the whale’s case oxygen and mass aren’t limiting factors at its size and size was a seemingly evolutionary advantage.

Anonymous 0 Comments

Higher concentration of oxygen in the air. That’s really it. That being said the blue whale is the largest known animal of any sort to ever exist but obviously marine animals have differences than land mammals. In the whale’s case oxygen and mass aren’t limiting factors at its size and size was a seemingly evolutionary advantage.

Anonymous 0 Comments

Oxygen levels is apparently a myth with maybe the exception of insects. They breathe using spiracles, essentially holes in their body or limbs. It’s a much less effective way of breathing than having lungs and puts a limit on their maximum size. So more oxygen in the atmosphere does potentially increases that allowed limit.

However for dinosaurs that isn’t the case. There were long periods of time when dinosaurs existed where oxygen levels were what they are today or even lower. From what I remember increasing in size was an evolutionary adaptation that worked for them and their bodies became increasingly specialised to “go large”. It was a wildly successful strategy and they dominated the ecosystem for hundreds of millions of years but it also made them especially vulnerable if the climate changed and they suddenly lost access to plentiful food and water. Such as when a large asteroid hits …

Anonymous 0 Comments

Oxygen levels is apparently a myth with maybe the exception of insects. They breathe using spiracles, essentially holes in their body or limbs. It’s a much less effective way of breathing than having lungs and puts a limit on their maximum size. So more oxygen in the atmosphere does potentially increases that allowed limit.

However for dinosaurs that isn’t the case. There were long periods of time when dinosaurs existed where oxygen levels were what they are today or even lower. From what I remember increasing in size was an evolutionary adaptation that worked for them and their bodies became increasingly specialised to “go large”. It was a wildly successful strategy and they dominated the ecosystem for hundreds of millions of years but it also made them especially vulnerable if the climate changed and they suddenly lost access to plentiful food and water. Such as when a large asteroid hits …

Anonymous 0 Comments

Higher concentration of oxygen in the air. That’s really it. That being said the blue whale is the largest known animal of any sort to ever exist but obviously marine animals have differences than land mammals. In the whale’s case oxygen and mass aren’t limiting factors at its size and size was a seemingly evolutionary advantage.

Anonymous 0 Comments

Oxygen levels is apparently a myth with maybe the exception of insects. They breathe using spiracles, essentially holes in their body or limbs. It’s a much less effective way of breathing than having lungs and puts a limit on their maximum size. So more oxygen in the atmosphere does potentially increases that allowed limit.

However for dinosaurs that isn’t the case. There were long periods of time when dinosaurs existed where oxygen levels were what they are today or even lower. From what I remember increasing in size was an evolutionary adaptation that worked for them and their bodies became increasingly specialised to “go large”. It was a wildly successful strategy and they dominated the ecosystem for hundreds of millions of years but it also made them especially vulnerable if the climate changed and they suddenly lost access to plentiful food and water. Such as when a large asteroid hits …

Anonymous 0 Comments

It’s important to remember that the biggest animal that has *EVER* lived is alive right now, the Blue Whale

Anonymous 0 Comments

Dinosaurs also existed for around 165 million years. In contrasts mammals have been round 65 millions years. There was a lot more time for evolution and natural selection to work out what worked best for their survival and reproduction. So in those extra 100 million years bigger was better.

Anonymous 0 Comments

It’s important to remember that the biggest animal that has *EVER* lived is alive right now, the Blue Whale

Anonymous 0 Comments

Dinosaurs also existed for around 165 million years. In contrasts mammals have been round 65 millions years. There was a lot more time for evolution and natural selection to work out what worked best for their survival and reproduction. So in those extra 100 million years bigger was better.

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