WEBVTT - How Did Prehistoric Animals Get So Big?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio, Hey

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<v Speaker 1>brain Stuff Lauren Vogelbaum. Here. There's ongoing debates about which

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<v Speaker 1>dinosaur might be the largest animal to have ever RealMed

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<v Speaker 1>the Earth. One candidate is a ninety eight million year

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<v Speaker 1>old skeleton of a long necked titanosaur discovered in northwest

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<v Speaker 1>Patagonia in in research published one in the journal Cretaceous Research.

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<v Speaker 1>The authors said that they believe it could be one

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<v Speaker 1>of the largest sauropods ever found, even larger than the

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<v Speaker 1>one on display at the American Museum of Natural History.

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<v Speaker 1>That's a hundred and twenty two ft long. That's thirty

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<v Speaker 1>seven ms. But why did priest work animals like these

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<v Speaker 1>get so big in the first place? After all, we

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<v Speaker 1>do still have megafauna that reached towering sizes, like elephants, rhinoceros,

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<v Speaker 1>and hippopotamus, But most of the largest land animals living

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<v Speaker 1>today would still look like little buddies next to the

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<v Speaker 1>literal mammoths of prehistory. And there are several hypotheses about

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<v Speaker 1>why these creatures grew so massive. Several studies have linked

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<v Speaker 1>environmental factors such as higher oxygen content in the air

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<v Speaker 1>to the expansion of huge sauropod dinosaurs in North America.

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<v Speaker 1>For example, a study published in twenty nineteen reported the

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<v Speaker 1>researchers using a new technique to analyze tiny amounts of

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<v Speaker 1>gas trapped inside two hundred and fifteen million year old

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<v Speaker 1>rocks from the Colorado Plateau and the Newark Basin. Jumps

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<v Speaker 1>in oxygen levels in layers of the rock correlate with

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<v Speaker 1>the first dinosaurs appearing in the area and then massive sauropods.

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<v Speaker 1>The existence of sauropods leads us to a second hypothesis

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<v Speaker 1>about why these animals grew so gigantic efficient food uptake.

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<v Speaker 1>The thought behind this idea is that because sarropods had

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<v Speaker 1>such long necks, they must have been more efficient eaters

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<v Speaker 1>than other large herbivores, meaning they could cover much larger

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<v Speaker 1>feeding grounds and reach food that was inaccessible to other

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<v Speaker 1>dinosaur wars. So, in theory, the massive sauropods must have

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<v Speaker 1>been able to grow larger than other dinosaurs because they

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<v Speaker 1>fed more efficiently. Then there's Cope's rule, which is the

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<v Speaker 1>hypothesis formulated by paleontologist Edward Cope that says that animals

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<v Speaker 1>in evolving lineages tend to get larger over time, and

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<v Speaker 1>a twelve study by the Department of paleo Biology at

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<v Speaker 1>the National Museum of Natural History found that Cope was

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<v Speaker 1>right well some of the time. Using advanced statistical methods,

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<v Speaker 1>the team used dinosaur femur bones to estimate animal size.

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<v Speaker 1>They then used that data in their statistical model to

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<v Speaker 1>look for too things, directional trends in size over time,

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<v Speaker 1>and whether there were any detectable upper limits for body size.

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<v Speaker 1>What they found was some groups or clades of dinosaurs,

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<v Speaker 1>including the long necked sauropods, do grow larger over time,

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<v Speaker 1>as Cope's rule suggests. However, others like therapods, which include

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<v Speaker 1>the popular Tyrannosaurus rex, did not. Other evidence points to

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<v Speaker 1>why prehistoric animals that flew grew so massive, and specifically,

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<v Speaker 1>it points to their bones and lungs. Parasaurs, for instance,

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<v Speaker 1>started out small, but some species ballooned to unbelievable proportions.

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<v Speaker 1>This could have been due in part to a highly

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<v Speaker 1>effective float through respiratory system, which allowed them the ability

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<v Speaker 1>to sustain flight. Take one of the largest flying pterosaurs

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<v Speaker 1>in the world as Dark Kids and I do hope

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<v Speaker 1>on saying that right. They had wingspans of thirty three

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<v Speaker 1>feet that's ten meters and weighed as much as four

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<v Speaker 1>hundred and forty pounds that's two hundred kilos. Studies have

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<v Speaker 1>shown that their bones were made up of intricate structures

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<v Speaker 1>that made them both super strong and stable, but also

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<v Speaker 1>super light. They may have been able to fly as

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<v Speaker 1>far as ten thousand miles that's sixteen thousand kilometers without

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<v Speaker 1>resting or eating, and the supersaurus is also thought to

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<v Speaker 1>have had extraordinarily light bones and a complex system of

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<v Speaker 1>air sacks, which could have allowed it to grow huge

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<v Speaker 1>without collapsing in on itself. They also had very efficient lungs,

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<v Speaker 1>so their respiration and heat exchange could better support their

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<v Speaker 1>larger size. Of course, all of the animals we've mentioned

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<v Speaker 1>were the top predators of their time, which made them

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<v Speaker 1>a lot less susceptible to becoming other animals dinner. One

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<v Speaker 1>exception to the animals being smaller these days rule are whales.

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<v Speaker 1>For example, the blue whale makes the supersourus seem small.

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<v Speaker 1>Blue whales grow on average to between seventy five and

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<v Speaker 1>nine ft in length that's about twenty three to twenty

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<v Speaker 1>seven and way about two hundred tons. Though it is

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<v Speaker 1>difficult to measure such a huge creature underwater. Being ocean bound,

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<v Speaker 1>they have buoyancy on their side, which makes it possible

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<v Speaker 1>for them to weigh three times with the supersourus wave

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<v Speaker 1>without their bodies collapsing. Today's episode is based on the

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<v Speaker 1>article why were so many prehistoric animals So big? On

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<v Speaker 1>how stuff works dot Com, written by Karen Kirkpatrick and

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<v Speaker 1>Sarah glime A. Brain Stuff is production by Heart Radio

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<v Speaker 1>in partnership with how stuff Works dot Com is produced

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