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  • Just how did the Tyrannosaurus rex get from oversized chicken to the colossal beast we

  • tend to see on the silver screen?

  • Well, were still digging for the answers.

  • Outside the confines of Jurassic Park, real-life scientists are always updating our ideas about

  • what dinosaurs may have looked like, and were constantly being surprised by their findings.

  • Like these brand new digital reconstructions of what baby T. rex’s may have looked like,

  • giving us new insight into their life cycle.

  • And beyond our curiosity about their beautiful exterior, related research has just revealed

  • that an early, ancestral species of T. rex was actually tiny!

  • Like the size of a small deer!

  • Turns out, the iconic T. rex is an enigmatic animal to understand.

  • To get us a little more situated in this story we talked with Mark Norell, who’s been working

  • on understanding the details of dinosaur life for his whole career.

  • He and his team have created digital reconstructions of T. rex hatchlings, and guystheyre

  • so cute.

  • And covered in feathers!

  • Mark Norell: “T. rex is kind of important because it's really an anomalous animal.

  • There's nothing else really like it at all.

  • And now that we're starting to get enough specimens of it that we can actually take

  • and really understand quite a bit about things like its growth, things like that ... Habits,

  • maybe a little bit about diet.

  • but it's certainly, I mean,

  • Most dinosaur specimens we only have one specimen of, or most dinosaur species.

  • But certainly with T. rex, we have 46 pretty well preserved specimens now.”

  • Until recently we didn’t have that much info about how the T. rex became the T. rex.

  • We knew they were a top end predator for about 15 million years up until their extinction

  • at the end of the Cretaceous period.

  • But when we try to go backward, before their mighty reign of terror began, there’s about

  • a 70 million year gap between giant T. rex and a medium-sized, primitive T. rex ancestor

  • we’d been able to unearth from the Jurassic period.

  • There was just nothing in the fossil record to indicate to us how, when, and how fast

  • T. rex went, in the words of one paleontologist, ‘from wallflower to prom king’.

  • So the chances of becoming a fossil are very, very, very, very, very small.

  • Chances of being a well preserved fossil is even much, much, much, much, smaller.

  • So we're working with not only a poor record, but a record which is flawed, also in the

  • sense that small animals don't preserve as large as big ones.

  • Howevernew fossils just unearthed in Utah are helping us put together the pieces.

  • These specimens are now thought to be the oldest Cretaceous tyrannosauroid remains ever

  • discovered in North America, and surprise!

  • Theyre the much smaller and faster ancestor of the huge, lumbering T. rex we know and

  • love.

  • This tiny ancestor of goliath is called Moros intrepidus, which cheerfully translates to

  • the harbinger of doom”.

  • It took this team 10 years of incredibly persistent excavation to find this key organism, helping

  • us not only piece together T. rex lineage, but also give us a sense of where they lived

  • and how they migrated through an ancient earth.

  • This update to the fossil record now tells us that at some point, the T. rex must have

  • made the journey from Asia, the home the very primitive tyrannasoid fossils we’d found

  • previously, to North America, where weve found this new in-betweener.

  • In addition to improving our understanding of where the T. rex came from and how it evolved

  • over time, were also starting to revisit how they grew up.

  • What happens in between a baby T. rex hatching and the full adult?

  • And WHY are its arms so tiny!?!

  • Mark: “I mean it grew to adult size in about 19 years, which is pretty remarkable..."

  • So that T. rex could grow to its immense size, for a while it was growing over two kilograms

  • a day for quite a while during its lifetime.

  • So that's surprising.

  • As babies, the little stumpy T. rex arms were more proportional to their body size, letting

  • them hold on to wriggling prey, like their smaller tyrannosauroid ancestors.

  • But as they had to pack on more and more weight even faster as they rose to prominence, more

  • of that development went to the head and neck, specially designed to brutally crush their

  • prey...leaving the arms just.

  • Hangin’.

  • The past ten years have been full of advancements to the computational and scientific tools

  • paleontologists use to analyze fossilized remains.

  • Techniques like synchrotron radiation and Raman spectroscopy represent non-invasive

  • imaging that let us see how the animals grew, to be able to see and count the layers of

  • bone they put down every year.

  • Mark: "So on a computation and technology side really a lot of has changed.

  • And it's changing really quickly now, just as we speak."

  • Advancements in both excavation and analysis are continuing for the T. rex niche of this

  • field and paleontology in generalwere starting to look at the fossil record in new

  • ways to help us gain a deeper understanding of well, everything.

  • From the origins of these species to what they looked like, what they ate, how they

  • interacted with each other, even what the ancient atmosphere was like ...there’s just

  • a wealth of information out there waiting to be dug up and discovered to tell us more

  • about our world and understand how we got to today.

  • Might as well start with the T. rex, huh?

  • While we won’t be bringing dinosaurs truly back to life any time soon, the American Museum

  • of Natural History is putting on quite the show with their T. rex recreations so if youre

  • in town you should check it out, or check them out online at the link in the description.

  • Let us know what your favorite T. rex fact is in the comments, and make sure you subscribe

  • to Seeker to find out what paleontologists will unearth next.

  • As always, thanks for watching!

Just how did the Tyrannosaurus rex get from oversized chicken to the colossal beast we

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