How long did a T. rex live?
AKI WATANABE (Research Associate, Division of Vertebrate Paleontology, American Museum of Natural History): How long did T.rex live?
[WATANABE speaks to camera. Text reads: “How long did a T. rex live?”]
[The American Museum of Natural History logo appears, with text below it reading “Space Vs Dinos” superimposed on illustrations of an asteroid and a dinosaur skull. It slides away and is replaced by an illustrated tyrannosaur surrounded by paparazzi with cameras [FLASHING].]
WATANABE: T. rex is not only the most popular dinosaur – it’s also the best studied.
[Illustrated humans gather around the tyrannosaur with magnifying glasses, rulers, and pluck a feather from it.]
WATANABE: So we know that T. rex lived up to about 30 years old.
[The humans disappear and text slides in front of the tyrannosaur: 30 years old. The whole image minimizes to reveal WATANABE behind it, accompanied by the text: Aki Watanabe, Paleontologist.]
WATANABE: Smaller dinosaurs like Velociraptor lived up to about 20-25 years old,
[An illustrated feathered Velociraptor appears below WATANABE next to the tyrannosaur, with the text: 20 years old.]
WATANABE: and gigantic long-necked sauropod dinosaurs lived to about 70 or even a hundred years old.
[An illustrated sauropod appears, with the text: 70 years old. All three illustrated dinosaurs fill the center of the screen in a row, with velociraptor to the left, T. rex in the middle, and the sauropod on the right.]
WATANABE: And T. rex sits in between in both size and lifespan.
[Arrows above and below the three dinosaurs, arrows draw in from the left. The top arrow has the accompanying text “Size” and the bottom arrow has the accompanying text “Lifespan.” Both arrows indicate that both increase towards the right, where the sauropod is.]
WATANABE: So just like the animals that live today, size did matter in terms of how long you lived.
[Below the dinosaurs, new illustrated animals appear. Below Velociraptor, a peacock; below T. rex, a rhinoceros; below the sauropod, a whale. WATANABE reappears on screen.]
WATANABE: How do we go about finding the age of these dinosaurs? Dinosaur fossils have growth rings, much like tree rings.
[Two images appear on either side of WATANABE: brown rings of wood, labelled “Tree” and brown rings of bone, labelled “Dino bone.’]
WATANABE: And so you can count the number of these lines
[On the image of the bone rings, four dotted lines extend.]
WATANABE: and roughly estimate the age of the dinosaur when it died.
[The dotted lines are labelled 1, 2, 3, and 4. The number 4 enlarges and reads “4 years.” An X-ray image of bone, labelled “Tyrannosaurus rex, age 28,” flips down from the top of the screen.]
WATANABE: We can also find out how the dinosaur grew during its lifetime
[Many dotted lines cover the Tyrannosaurus bone in concentric lines, like tree rings. A new x-ray image of bone, labelled “Coelophysis bauri, age 3,” flips down from the top of the screen. Three dotted parallel lines appear over the bone.]
WATANABE: by measuring the amount of bone between these lines.
[Between the lines, two orange brackets appear to indicate distance. A new x-ray image of bone, labelled “Haya griva, age 6,” flips down from the top of the screen.]
WATANABE: The greater the distance, the dinosaur grew more quickly, and the shorter the distance, the dinosaur’s growth slowed.
[Two lines, spaced decently far apart, appear over the Haya griva bone. A bracket appears between the lines with the text “Fast growth.” Three lines spaced very close together appear over the same bone x-ray. A bracket appears over the lines with the text “Slow growth.” WATANABE reappears on screen.]
WATANABE: From looking at different T. rex bones, we can create the life history of T. rex.
[A generic bone labelled “T. rex” pops up next to WATANABE. Several more appear and they funnel into a book labelled “T. rex: A Scrapbook.” The screen whites out. An illustration of a Polaroid picture comes into focus; in the frame is a close up of an egg with a crack in it, labelled “Here I come!” A second Polaroid image comes into focus, with a small illustrated fluffy dinosaur, labelled “Baby me.”]
WATANABE: T. rex started out small, and weighed about 30 kg, or just over 60 pounds when it was two years old.
[Two new Polaroid frames slide on top of the previous two. One shows an illustration of a baby T. rex, labelled “Terrible twos,” and the other shows a German shepherd, labelled “As much as a German shepherd.” At the top of the screen, text appears: “ ~ 30 kg/66 lbs”]
WATANABE: And it steadily grew until its early teen years,
[A dinosaur claw drags the Polaroids offscreen and puts a new Polaroid on screen. This has a slightly older-looking illustrated T. rex standing in front of growth markers on a wall, while an offscreen adult T. rex holds a piece of chalk. The label reads “Getting huge!”]
WATANABE: up to around 2,000 kilograms, or 4500 pounds, which is about the weight of a rhino.
[Two new Polaroids cover this one. One shows a full illustration of a juvenile T. rex, with the label “Awkward teen years,” and the other shows a rhinoceros with the label “As much as a rhinoceros.” At the top of the screen, text appears: “~ 2,000 kg/4,500 lbs.” WATANABE reappears on screen.]
WATANABE: While we have this strong image of an adult T. rex chomping on large herbivorous dinosaurs,
[Next to WATANABE, a T. rex looms over a Triceratops. The Triceratops quickly turns and runs offscreen when the T. rex opens its mouth.]
WATANABE: juvenile T. rexes were much smaller,
[Illustrations of a juvenile T. rex and an adult T. rex appear on screen. Brackets indicate that the juvenile is “smaller, I GUESS” and the adult is “flippin’ huge.”]
WATANABE: they had much lower bite force,
[Circles are drawn in around each of the dinosaurs’ jaws, with the juveniles indicated to be “just regular bitey” and the adults to be “extra bitey.”]
WATANABE: and they were more agile –
[A label pointing to the juvenile reads “Lamborghini” and a label pointing to the adult reads “18-wheeler.”]
WATANABE: so we believe they fed on more moderately sized animals.
[The illustration is replaced by an illustrated Polaroid with a dinner table holding a Triceratops skull and a Pachycephalosaurus skull, labelled “Dinner for mom and me!” WATANABE reappears on screen.]
WATANABE: And at this point, T. rex went through a massive growth spurt during its teenage years,
[A line is drawn growing up from the bottom of the screen to the top in a curve. Text reads: Growth spurt. An illustration of a juvenile T. rex follows the line until halfway through the curve, then morphs into an adult T. rex.]
WATANABE: from about age 13 all the way to about 20 years old, much like humans.
[Beneath the words “Growth spurt,” the text “Age 13 – 20” appears.]
WATANABE: But unlike humans, T. rexes grew up to 2 kgs, not per year, per month, or per week – but per day.
[A human and a juvenile T. rex appear on either side of the screen. On the human side, one 2kg weight falls from the top of the screen. 2kg weights fall slowly on the T. rex side, increasingly, until they are filling the screen.]
WATANABE: And then T. rex reached its adult size around the age of twenty,
[A Polaroid of an adult T. rex wearing a tiny graduation cap comes into focus, with the label “Summa cum laude in biting.”]
WATANABE: where it reached an astonishing weight of 6,000 kg, or over 13,000 lbs, which is about the same weight as an African elephant.
[Two new Polaroids cover this one. One shows a full illustration of an adult T. rex, with the label “#adulting,” and the other shows an elephant with the label “As much as an African elephant.” At the top of the screen, text appears: “~ 6,000 kg/13,000 lbs.” WATANABE reappears on screen.]
WATANABE: Once it reached its adult size, T. rex didn’t grow much bigger, or even much older.
[Polaroids flip next to WATANABE, showing an adult T. rex. Each Polaroid is labelled sequentially (“20 years old,” “21 years old,” and so on) without a change until it gets to “25 years old,” where a gravestone appears.]
WATANABE: The oldest known T. rex is Sue, which is 28 years old.
[A photo of a large fossil T. rex skull in the ground with two paleontologists smiling next to it appears. A dotted line goes around the skull and text reads: “Sue – 28 years old.”]
WATANABE: And this is a larger trend among dinosaurs,
[A number line is drawn out, with brackets for the groups “1-6,” “7-12,” “13-18,” “19-24,” and “25-30.” A label beneath the number line reads: “Age at death.”]
WATANABE: where we only tend to find young or young adult fossils and not many fully grown adults.
[Dinosaur skull and bone illustrations fill up each of the brackets, with the vast majority in the “13-18” age group. A label in the top left corner reads: “*from two studies looking at T. rex specimen age.” A bracket around the 13-18 group reads “young adult.” It disappears and a bracket around the “1-6” and “7-12” groups appears with the label “juveniles” and a bracket around the “19-24” and “25-30” groups appears with the label “fully grown adults + elders.”]
WATANABE: And so we think that dinosaurs lived fast and died young.
[A wheel runs over the number line and the skull and bones topple over. The camera zooms out quickly to reveal a T. rex on a motorcycle. Sunglasses fall into place on the T. rex and lightning bolts shoot out from the motorcycle while a [GUITAR WAILS]. Text from the T. rex reads: “deal with it.” The T. rex does a wheelie off screen. A projector screen pulls down from the top of the screen. ]
WATANABE: Although we’re just left with the bones of T. rex, as you can see, we can learn much more than just its anatomy.
[On the projector screen, we see images of the American Museum of Natural History’s famous T. rex fossil specimen.]
WATANABE: And you can bet that with new fossils and new technologies,
[On the projector screen, we see a 3D rotating image of a T. rex skull.]
WATANABE: we’ll learn even more about the lives of these dinosaurs.
[Another Polaroid comes into focus on screen, with the baby, juvenile, and adult T. rex all together. The label reads: “The whole family!”]
[Credits roll. WATANABE continues to speak in the lower right hand of the screen.]
WATANABE: Thanks for watching, and if you love T. rex and want to learn even more about this amazing dinosaur, make sure to come visit the American Museum of Natural History where we’ll be having a special exhibit all about T. rex. Don’t forget to subscribe to the AMNH channel for more videos like this.
Paleontologist Aki Watanabe reveals what took Tyrannosaurus rex from tiny hatchling to mega predator, as well as the evidence scientists use to learn more about a dinosaur’s lifespan.
If you want to know about the lifespan of our Sun, watch this week's Space video. To learn more about the life of the ultimate predator, visit the special exhibition, T. rex: The Ultimate Predator.