Feels like there was a lot more megafauna in prehistoric earth than there are today
In: 20
One hypothesis has to do with the higher atmospheric oxygen level in prehistoric times. When an organism gets larger, it’s surface area : volume ratio decreases, **rapidly.** Hence, a larger animal would find it more difficult to get sufficient oxygen than a smaller one (as more surface area allows for more gas exchange). The higher O2 levels in prehistoric times would have allowed larger animals to get sufficient oxygen
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