Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,
Speaker 1: Lorenvolk bum here with a classic episode from our former host,
Speaker 1: Christian Sagar. This one is near and dear to me.
Speaker 1: Our topic for the day is why the Tyrannosaurus Rex
Speaker 1: have such tiny arms? A brain Stuff it's Christian Sagar.
Speaker 1: With a name that literally means tyrant lizard king, you'd
Speaker 1: assume that Tyrannosaurus rex would get a bit more respect,
Speaker 1: but the giant predators disproportionately small arms have been the
Speaker 1: subject of ridicule for decades. They are also a scientific puzzle.
Speaker 1: More than one hundred years after discovery of this species,
Speaker 1: experts still don't know why a huge animal, one that
Speaker 1: could reach links of forty feet or twelve meters or more,
Speaker 1: had four limbs that weren't much longer than an adult humans.
Speaker 1: If the arms were limp muscle free pegs, it'd easy
Speaker 1: to assume that they serve no purpose. However, the evidence
Speaker 1: hints at a more complicated story. A few studies have
Speaker 1: argued that, judging by the muscle scars left behind on
Speaker 1: t rex limb bones, a full grown dinosaur could curl
Speaker 1: more than two hundred and twenty pounds or one hundred
Speaker 1: rams with each one of their biceps. Then again, this
Speaker 1: isn't as impressive as it sounds. Thomas ore Holtz, a
Speaker 1: vertebrate paleontologist at the University of Maryland, tells us that
Speaker 1: some people like to overrate tyrannosaurus is upper body strength.
Speaker 1: That figure from before only translates to about one point
Speaker 1: to five per cent of the dinosaurs total body weight,
Speaker 1: which may have been in the ballpark of around eight
Speaker 1: tons or eight thousand kilograms. Holtz says that's like a
Speaker 1: two hundred pound or nine man being proud of the
Speaker 1: ability to curl two point five pounds or one kilogram.
Speaker 1: On these grounds, A few experts have concluded that Tyrannosaurus's
Speaker 1: arms were either functionless or seldom used, but not all
Speaker 1: paleontologists by this idea. For his money, Kenneth Carpenter of
Speaker 1: Utah State University thinks the little limbs made great hunting tools.
Speaker 1: In two thousand eight, he and fellow paleontologist Christine Lipkin
Speaker 1: compared the five Tyrannosaurus rex wishbones or ferculars that were
Speaker 1: known to science at the time. Shaped like a giant boomerang,
Speaker 1: the fercular sits between the shoulder blades. Three of the
Speaker 1: five wishbones that Carpenter and Lipkin studied show telltale signs
Speaker 1: of injury. Among these were stress fractures, which must have
Speaker 1: re healed in life. So what does this mean? While
Speaker 1: according to Carpenter, the four limbs were subjected to a
Speaker 1: great deal of repetitive stress, which was not uniform or steady. Instead,
Speaker 1: there were moments of x e straordinarily great force applied
Speaker 1: to the arms. The most likely explanation is that t
Speaker 1: Rex used its four limbs to grab hold of large
Speaker 1: struggling prey. A plus sized thrashing victim could easily fracture
Speaker 1: the carnivores wishbone or at least tear a few arm
Speaker 1: muscles loose. Other ideas about the purpose of t rex
Speaker 1: arms have nothing to do with subduing victims. One school
Speaker 1: of thought involves naptime. Perhaps after a good night's sleep,
Speaker 1: Torannosaurus used those arms to push itself up off the ground,
Speaker 1: or maybe they had a sexier function. Henry Fairfield Osborne,
Speaker 1: the paleontologists who named this species back in nineteen o five,
Speaker 1: believed that males used their four limbs to grab hold
Speaker 1: of their mates as Holts and others have admitted there
Speaker 1: simply isn't enough evidence at this time to conclusively refute
Speaker 1: or verify any of these notions. Much is often the
Speaker 1: nature of paleontology. Today's episode was written by Mark Fancini
Speaker 1: and produced by Dylan Fagan and Tyler Clang. For more
Speaker 1: in this and lots of other topics, visit how stuff
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