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How do you find a dinosaur?
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Sounds impossible, doesn't it?
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It's not.
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And the answer relies on a formula
that all paleontologists use.
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And I'm going to tell you the secret.
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First, find rocks of the right age.
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Second, those rocks
must be sedimentary rocks.
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And third, layers of those rocks
must be naturally exposed.
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That's it.
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Find those three things
and get yourself on the ground,
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chances are good
that you will find fossils.
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Now let me break down this formula.
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Organisms exist only during certain
geological intervals.
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So you have to find
rocks of the right age,
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depending on what your interests are.
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If you want to find trilobites,
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you have to find the really,
really old rocks of the Paleozoic --
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rocks between a half a billion
and a quarter-billion years old.
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Now, if you want to find dinosaurs,
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don't look in the Paleozoic,
you won't find them.
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They hadn't evolved yet.
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You have to find the younger
rocks of the Mesozoic,
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and in the case of dinosaurs,
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between 235 and 66 million years ago.
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Now, it's fairly easy to find rocks
of the right age at this point,
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because the Earth is, to a coarse degree,
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geologically mapped.
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This is hard-won information.
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The annals of Earth history
are written in rocks,
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one chapter upon the next,
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such that the oldest pages are on bottom
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and the youngest on top.
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Now, were it quite that easy,
geologists would rejoice.
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It's not.
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The library of Earth is an old one.
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It has no librarian to impose order.
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Operating over vast swaths of time,
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myriad geological processes
offer every possible insult
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to the rocks of ages.
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Most pages are destroyed
soon after being written.
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Some pages are overwritten,
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creating difficult-to-decipher palimpsests
of long-gone landscapes.
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Pages that do find sanctuary
under the advancing sands of time
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are never truly safe.
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Unlike the Moon --
our dead, rocky companion --
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the Earth is alive, pulsing
with creative and destructive forces
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that power its geological metabolism.
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Lunar rocks brought back
by the Apollo astronauts
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all date back to about the age
of the Solar System.
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Moon rocks are forever.
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Earth rocks, on the other hand,
face the perils of a living lithosphere.
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All will suffer ruination,
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through some combination
of mutilation, compression,
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folding, tearing, scorching and baking.
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Thus, the volumes of Earth history
are incomplete and disheveled.
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The library is vast and magnificent --
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but decrepit.
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And it was this tattered complexity
in the rock record
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that obscured its meaning
until relatively recently.
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Nature provided no card catalog
for geologists --
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this would have to be invented.
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Five thousand years after the Sumerians
learned to record their thoughts
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on clay tablets,
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the Earth's volumes remained
inscrutable to humans.
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We were geologically illiterate,
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unaware of the antiquity
of our own planet
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and ignorant of our connection
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to deep time.
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It wasn't until the turn
of the 19th century
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that our blinders were removed,
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first, with the publication
of James Hutton's "Theory of the Earth,"
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in which he told us that the Earth
reveals no vestige of a beginning
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and no prospect of an end;
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and then, with the printing
of William Smith's map of Britain,
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the first country-scale geological map,
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giving us for the first time
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predictive insight into where
certain types of rocks might occur.
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After that, you could say things like,
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"If we go over there,
we should be in the Jurassic,"
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or, "If we go up over that hill,
we should find the Cretaceous."
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So now, if you want to find trilobites,
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get yourself a good geological map
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and go to the rocks of the Paleozoic.
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If you want to find dinosaurs like I do,
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find the rocks of Mesozoic and go there.
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Now of course, you can only make
a fossil in a sedimentary rock,
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a rock made by sand and mud.
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You can't have a fossil
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in an igneous rock formed
by magma, like a granite,
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or in a metamorphic rock
that's been heated and squeezed.
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And you have to get yourself in a desert.
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It's not that dinosaurs
particularly lived in deserts;
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they lived on every land mass
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and in every imaginable environment.
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It's that you need to go to a place
that's a desert today,
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a place that doesn't have
too many plants covering up the rocks,
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and a place where erosion is always
exposing new bones at the surface.
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So find those three things:
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rocks of the right age,
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that are sedimentary rocks, in a desert,
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and get yourself on the ground,
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and you literally walk
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until you see a bone
sticking out of the rock.
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Here's a picture that I took
in Southern Patagonia.
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Every pebble that you see
on the ground there
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is a piece of dinosaur bone.
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So when you're in that right situation,
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it's not a question of whether
you'll find fossils or not;
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you're going to find fossils.
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The question is: Will you find something
that is scientifically significant?
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And to help with that, I'm going to add
a fourth part to our formula,
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which is this:
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get as far away from other
paleontologists as possible.
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(Laughter)
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It's not that I don't like
other paleontologists.
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When you go to a place
that's relatively unexplored,
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you have a much better chance
of not only finding fossils
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but of finding something
that's new to science.
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So that's my formula
for finding dinosaurs,
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and I've applied it all around the world.
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In the austral summer of 2004,
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I went to the bottom of South America,
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to the bottom of Patagonia, Argentina,
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to prospect for dinosaurs:
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a place that had terrestrial
sedimentary rocks of the right age,
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in a desert,
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a place that had been barely visited
by paleontologists.
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And we found this.
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This is a femur, a thigh bone,
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of a giant, plant-eating dinosaur.
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That bone is 2.2 meters across.
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That's over seven feet long.
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Now, unfortunately,
that bone was isolated.
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We dug and dug and dug,
and there wasn't another bone around.
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But it made us hungry to go back
the next year for more.
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And on the first day
of that next field season,
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I found this: another two-meter femur,
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only this time not isolated,
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this time associated with 145 other bones
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of a giant plant eater.
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And after three more hard,
really brutal field seasons,
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the quarry came to look like this.
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And there you see the tail
of that great beast wrapping around me.
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The giant that lay in this grave,
the new species of dinosaur,
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we would eventually call
"Dreadnoughtus schrani."
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Dreadnoughtus was 85 feet
from snout to tail.
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It stood two-and-a-half stories
at the shoulder,
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and all fleshed out in life,
it weighed 65 tons.
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People ask me sometimes,
"Was Dreadnoughtus bigger than a T. rex?"
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That's the mass of eight or nine T. rex.
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Now, one of the really cool things
about being a paleontologist
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is when you find a new species,
you get to name it.
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And I've always thought it a shame
that these giant, plant-eating dinosaurs
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are too often portrayed as passive,
lumbering platters of meat
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on the landscape.
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(Laughter)
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They're not.
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Big herbivores can be surly,
and they can be territorial --
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you do not want to mess with a hippo
or a rhino or a water buffalo.
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The bison in Yellowstone injure
far more people than do the grizzly bears.
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So can you imagine a big bull,
65-ton Dreadnoughtus
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in the breeding season,
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defending a territory?
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That animal would have been
incredibly dangerous,
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a menace to all around, and itself
would have had nothing to fear.
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And thus the name, "Dreadnoughtus,"
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or, "fears nothing."
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Now, to grow so large,
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an animal like Dreadnoughtus
would've had to have been
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a model of efficiency.
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That long neck and long tail help it
radiate heat into the environment,
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passively controlling its temperature.
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And that long neck also serves
as a super-efficient feeding mechanism.
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Dreadnoughtus could stand
in one place and with that neck
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clear out a huge envelope of vegetation,
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taking in tens of thousands of calories
while expending very few.
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And these animals evolved
a bulldog-like wide-gait stance,
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giving them immense stability,
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because when you're 65 tons,
when you're literally as big as a house,
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the penalty for falling over
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is death.
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Yeah, these animals are big and tough,
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but they won't take a blow like that.
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Dreadnoughtus falls over,
ribs break and pierce lungs.
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Organs burst.
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If you're a big 65-ton Dreadnoughtus,
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you don't get to fall down
in life -- even once.
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Now, after this particular
Dreadnoughtus carcass was buried
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and de-fleshed by a multitude
of bacteria, worms and insects,
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its bones underwent a brief metamorphosis,
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exchanging molecules with the groundwater
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and becoming more and more
like the entombing rock.
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As layer upon layer
of sediment accumulated,
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pressure from all sides
weighed in like a stony glove
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whose firm and enduring grip held
each bone in a stabilizing embrace.
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And then came the long ...
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nothing.
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Epoch after epoch of sameness,
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nonevents without number.
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All the while, the skeleton lay
everlasting and unchanging
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in perfect equilibrium
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within its rocky grave.
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Meanwhile, Earth history unfolded above.
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The dinosaurs would reign
for another 12 million years
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before their hegemony was snuffed out
in a fiery apocalypse.
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The continents drifted. The mammals rose.
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The Ice Age came.
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And then, in East Africa,
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an unpromising species of ape
evolved the odd trick of sentient thought.
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These brainy primates were not
particularly fast or strong.
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But they excelled at covering ground,
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and in a remarkable diaspora
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surpassing even the dinosaurs' record
of territorial conquest,
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they dispersed across the planet,
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ravishing every ecosystem
they encountered,
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along the way, inventing culture
and metalworking and painting
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and dance and music
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and science
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and rocket ships that would eventually
take 12 particularly excellent apes
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to the surface of the Moon.
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With seven billion peripatetic
Homo sapiens on the planet,
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it was perhaps inevitable
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that one of them would eventually
trod on the grave of the magnificent titan
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buried beneath the badlands
of Southern Patagonia.
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I was that ape.
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And standing there, alone in the desert,
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it was not lost on me
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that the chance of any one individual
entering the fossil record
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is vanishingly small.
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But the Earth is very, very old.
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And over vast tracts of time,
the improbable becomes the probable.
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That's the magic of the geological record.
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Thus, multitudinous creatures
living and dying on an old planet
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leave behind immense numbers of fossils,
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each one a small miracle,
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but collectively, inevitable.
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Sixty-six million years ago,
an asteroid hits the Earth
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and wipes out the dinosaurs.
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This easily might not have been.
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But we only get one history,
and it's the one that we have.
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But this particular reality
was not inevitable.
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The tiniest perturbation
of that asteroid far from Earth
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would have caused it to miss
our planet by a wide margin.
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The pivotal, calamitous day during which
the dinosaurs were wiped out,
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setting the stage
for the modern world as we know it
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didn't have to be.
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It could've just been another day --
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a Thursday, perhaps --
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among the 63 billion days
already enjoyed by the dinosaurs.
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But over geological time,
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improbable, nearly impossible events
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do occur.
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Along the path from our wormy,
Cambrian ancestors
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to primates dressed in suits,
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innumerable forks in the road
led us to this very particular reality.
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The bones of Dreadnoughtus
lay underground for 77 million years.
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Who could have imagined
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that a single species of shrew-like mammal
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living in the cracks of the dinosaur world
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would evolve into sentient beings
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capable of characterizing
and understanding
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the very dinosaurs they must have dreaded?
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I once stood at the head
of the Missouri River
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and bestraddled it.
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There, it's nothing more
than a gurgle of water
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that issues forth from beneath a rock
in a boulder in a pasture,
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high in the Bitterroot Mountains.
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The stream next to it
runs a few hundred yards
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and ends in a small pond.
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Those two streams -- they look identical.
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But one is an anonymous trickle of water,
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and the other is the Missouri River.
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Now go down to the mouth
of the Missouri, near St. Louis,
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and it's pretty obvious
that that river is a big deal.
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But go up into the Bitterroots
and look at the Missouri,
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and human prospection does not
allow us to see it as anything special.
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Now go back to the Cretaceous Period
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and look at our tiny, fuzzball ancestors.
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You would never guess
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that they would amount
to anything special,
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and they probably wouldn't have,
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were it not for that pesky asteroid.
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Now, make a thousand more worlds
and a thousand more solar systems
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and let them run.
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You will never get the same result.
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No doubt, those worlds would be
both amazing and amazingly improbable,
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but they would not be our world
and they would not have our history.
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There are an infinite number of histories
that we could've had.
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We only get one, and wow,
did we ever get a good one.
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Dinosaurs like Dreadnoughtus were real.
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Sea monsters like the mosasaur were real.
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Dragonflies with the wingspan of an eagle
and pill bugs the length of a car
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really existed.
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Why study the ancient past?
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Because it gives us perspective
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and humility.
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The dinosaurs died in the world's
fifth mass extinction,
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snuffed out in a cosmic accident
through no fault of their own.
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They didn't see it coming,
and they didn't have a choice.
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We, on the other hand, do have a choice.
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And the nature of the fossil record
tells us that our place on this planet
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is both precarious
and potentially fleeting.
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Right now, our species is propagating
an environmental disaster
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of geological proportions
that is so broad and so severe,
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it can rightly be called
the sixth extinction.
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Only unlike the dinosaurs,
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we can see it coming.
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And unlike the dinosaurs,
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we can do something about it.
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That choice is ours.
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Thank you.
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(Applause)