MISSOULA- Fossils show that movies like Jurassic Park were right — dinosaurs were big. Really Big! A T-Rex was longer than a school bus.
This edition of A Wilder View looks at what happened to make these lizards so big, and why there are very few true giants alive today.
Welcome to the world of giants!
One sea scorpion that existed 400 million years ago was over 8 feet tall. Its relatives we see today like crabs, lobsters, and spiders are far smaller.
Today we can still see giants like elephants and whales.
But long before them, every animal seemed to be the heavyweight champion of its time.
Although massive animals still exist today prehistorically there were far more animals of gigantic proportions.
Ancient atmospheres had higher concentrations of oxygen.
According to Arizona State University, around 300 million years ago oxygen levels peaked at around 31%, compared to 21% oxygen in our atmosphere today.
It turns out that when there's more oxygen in the air, animals can develop more efficient respiratory systems, enabling them to grow bigger, faster, and stronger.
But it's not just about the environment. It also takes time. It took about 25 million years for the first mammals to reach a ton in weight.
According to a 2016 study published in the journal PLOS ONE, gigantism depends on the environment to be just right for a creature to grow to gigantic proportions.
The better the food, the faster and bigger they would grow. Most enormous creatures are herbivores releasing lots of energy as heat during digestion.
Big herbivores like elephants are basically walking breweries, producing lots of heat during digestion!
They're also great at retaining body heat because they have a lot of volume compared to their skin surface which is why they stay relatively hairless and cool themselves off with mud baths.
Sauropod dinosaurs — which are the largest dinosaurs ever — had air sacs along their skeleton like modern birds.
These air sacs helped them dissipate heat from their massive bodies and kept their bones light, yet strong enough to support their weight.
This allowed them to grow to enormous sizes without collapsing in on themselves!
Dinosaurs seem to be the first thought when we imagine giant prehistoric creatures, but at one point there were sloths bigger than cars, there were seagull-sized dragonflies and even rodents towering at 10 feet high.
And you’re likely thankful we don’t see those today, but amazingly, we still can view the largest creature to ever exist in history -- blue whales, creatures the size of 40 elephants.
As we're just beginning to understand the reasons for their size it is becoming apparent their gigantism is tied closely to two things — their choice of prey, and the coincidence of their evolution with a global increase in the upwelling of nutrient-rich water from the depths of the ocean.
As we continue to learn more about these magnificent creatures, who knows what other secrets of the world of giants we may uncover?
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