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Speaker 1: Welcome to brain Stuff, a production of iHeart Radio. Hey

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Speaker 1: They're brain Stuff, Lauren Vogelbaum Here. They lived about thirty

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Speaker 1: million years apart and never set foot on the same continent.

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Speaker 1: Yet Giganetosaurus carolini i is always getting compared to the

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Speaker 1: world's most popular dinosaur, the beloved and well known Torannosaurus rex.

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Speaker 1: Toranosaurus rex has been a media darling since arguably nineteen

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Speaker 1: o six, when The New York Times called it the

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Speaker 1: prize fighter of antiquity. Named just one year prior, this

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Speaker 1: big beast was already making a splash over at the

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Speaker 1: American Museum of Natural History in Manhattan. Today, we know

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Speaker 1: that an adult t Rex could stand twelve feet or

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Speaker 1: about three and a half meters tall at the hip

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Speaker 1: and measure forty feet or twelve meters long. As such,

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Speaker 1: Torannosaurus was one of the largest predators to ever walk

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Speaker 1: the earth, But hold your horses. A handful of other

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Speaker 1: meat eating dinos rivaled or possibly exceeded these creatures in size.

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Speaker 1: Jiganosaurus belongs to this elite group, and it's part of

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Speaker 1: a dinosauran mystery that's never been solved. T Rex and

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Speaker 1: Jagonatosaurus were both representatives of the Therapoda clade, a clade

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Speaker 1: being a group of organisms that includes a common ancestor

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Speaker 1: species and all of its presumed descendants, hollow, boned and bipedal.

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Speaker 1: The therapods were and are a highly successful bunch. On

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Speaker 1: the list of documented therapods, you'll find every carnivorous dinosaur

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Speaker 1: ever discovered, quite a few plant gobbling species, and all

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Speaker 1: birds living and extinct. The last non avian dinosaurs were

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Speaker 1: wiped out at the close of the Cretaceous Period, an

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Speaker 1: expanse of geologic time that lasted from a hundred forty

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Speaker 1: five to sixty six million years ago. Its conclusion marked

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Speaker 1: the end of the Mesozoic era, sometimes called the Age

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Speaker 1: of the Dinosaurs. Tyrannosaurus rex lived in North America during

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Speaker 1: the Twilight of the Cretaceous, making its evolutionary debut around

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Speaker 1: sixty eight million years before the present. Our buddy, Gigonatosaurus

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Speaker 1: was the product of another time and a whole different

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Speaker 1: land mass. Native to western Argentina, it came along much

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Speaker 1: earlier in the Cretaceous, roughly ninety seven million years ago.

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Speaker 1: South America was a realm of giants. Back then, huge

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Speaker 1: sauropods or long necked dinosaurs roamed the countryside, with some

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Speaker 1: species stretching around fifty feet or fifteen meters long. Rounding

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Speaker 1: out the local beasti area were crocodilians, early snakes, and

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Speaker 1: beaked herbivores. No doubt Gigonatosaurus kept its neighbors on guard.

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Speaker 1: That therapods discovery was first announced in by paleontologists rudolful

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Speaker 1: Choria and Leonardo Salgado. In all the years since, we

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Speaker 1: have yet to find a complete skeleton. However, the backbones

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Speaker 1: and tail vertebrate at art disposal suggest Gigonatosaurus was at

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Speaker 1: least forty one ft or twelve and a half meters

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Speaker 1: in length, so Gigonatosaurus might have been slightly longer than Tyrannosaurus.

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Speaker 1: On the other hand, a paper published in argued that

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Speaker 1: t Rex had a much heavier build. Using the circumference

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Speaker 1: of its upper leg bone, Roger Benson and his colleagues

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Speaker 1: calculated that a mature Giganetosaurus weighed about thirteen thousand, five

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Speaker 1: hundred pounds or about six thousand, one hundred kilos. The

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Speaker 1: same technique put t Rex at a whopping seventeen thousand

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Speaker 1: pounds or seven thousand, seven hundred kilos weight gaps are

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Speaker 1: all well and good, but the jaws tell better stories.

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Speaker 1: Anatomical evidence suggests that these two carnivores used very different

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Speaker 1: methods to bring down their prey. The teeth of Tyrannosaurus

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Speaker 1: were thick and sort of banana shaped and would have

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Speaker 1: excelled a crushing bone. In contrast, Giganetosaurus had tall, skinny

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Speaker 1: teeth that looked an awful lot like recurved kitchen knives

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Speaker 1: serrated on both sides. These pearly whites were housed inside

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Speaker 1: a narrow snout. By the way, Giganetosaurus had a monstrous skull,

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Speaker 1: soient estimate this noggin was around six ft or two

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Speaker 1: meters long. Combine all of these features and you're looking

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Speaker 1: at a therapod that probably killed by slicing ribbons of

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Speaker 1: meat off of its unfortunate prey, as opposed to shattering bones.

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Speaker 1: Once bitten, a victim may have bled out while the

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Speaker 1: carnivore lurked nearby. Giganetosaurus hails from one of the fossil

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Speaker 1: records most intimidating families, the Cacara Donta swords. If you're

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Speaker 1: into sharks, that name should ring a bell. Scientists called

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Speaker 1: the Great white the car cardon Cacarius. Likewise, the word

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Speaker 1: cocardonto sword roughly means shark toothed lizard in Greek. Well

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Speaker 1: we spoke by email with Steve Brusatti, a paleontologist at

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Speaker 1: the University of Edinburgh who studied these remarkable therapods and

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Speaker 1: happens to be a scientific advisor for the next Jurassic

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Speaker 1: World movie. He said, the roster of Cacara donta sword

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Speaker 1: fossils has expanded tremendously over the last decade as people

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Speaker 1: have found new fossils all over the world, particularly in

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Speaker 1: South americ in Africa, but also in Asia and Europe.

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Speaker 1: Most kacar dontosaurids, like Giganotosaurus were giant meat eating dinosaurs

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Speaker 1: with deep jaws and sharp, thin, almost shark like teeth.

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Speaker 1: They were the largest and most formidable predators in many

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Speaker 1: ecosystems during the early to middle part of the Cretaceous

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Speaker 1: before the rise of Tyrannosaurus. Indeed, t Rex itself had

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Speaker 1: some puny forebears. The first members of its lineage were

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Speaker 1: human sized predators that showed up around a hundred and

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Speaker 1: seventy million years ago. Giant Tyrannosaurus wouldn't start evolving until

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Speaker 1: the late Cretaceous period, after the mighty cocar Donta saurids

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Speaker 1: died out. Brussadi said that this changeover remains a mystery.

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Speaker 1: We really don't know why it happened, and it's one

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Speaker 1: of the biggest remaining mysteries of dinosaur evolution in my opinion.

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Speaker 1: Today's episode was written by Mark Mancini and produced by

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Speaker 1: Tyler Klang. For more on this and lots of other

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Speaker 1: thunderous topics, visit has to Forks dot com. Rain Stuff

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