5:09
Contrary to popular belief, we have this tremendous record of transitional
forms going from fish to amphibians, for example, from dinosaurs to birds,
from land living deer-like animals to whales and from early Hominids to us.
And therefore, these transitional forms give us a real sense of the flow,
the ebb and flow of the great story as it happened on earth.
>> So in terms of reading the bones, the historians read the record, but
you're reading this fossil record.
Can you give us a feeling for maybe the thresholds of change or
what are you reading there?
>> I like to think of paleontologists as sleuths and
we're constantly looking for clues, and so the bones are our primary record.
But, really that's only part of it, in the sense that we're trying to reinterpret
environments as well as animals and put those environments back together.
So we have records not only of back boned animals that happen to preserve bones,
but also sometimes of insects, of rocks and
the environments that they preserve, of bacteria and fungi and all these other
things that can actually help us to reconstruct entire ancient ecosystems.
And it's really only in the past 20 years that paleontology has moved beyond
sort of this stamp collecting phase of finding something and giving it a name and
instead, moved to this more integrative aspect of the science where we
really are reconstructing ancient worlds.
>> So you need other disciplines to help you with that?
>> Yeah, in fact, paleontology's a wonderful discipline in the sense that it
sits on the cusp of two other major disciplines.
Biology on the one side or life science and geology or earth science on the other
and many paleontologists are trained in the earth sciences, many in the life
sciences and they often work back and forth in different departments.
And so I think, by definition,
paleontologists are sort of jacks of all trades, and interdisciplinary.
>> So how long did the dinosaurs populate the planet?
Give us that feeling of time.
>> Yeah, dinosaurs first appeared about 230 million years ago and the big
ones anyway, all except the birds, were wiped out just over 65 million years ago.
So it's around 160 to 170 million years that dinosaurs were
the dominant animals on the planet.
And it seems like such a long time ago, but the interesting thing is that
Tyrannosaurus Rex, that lived at the very end of the Mesozoic Era,
the age of dinosaurs, is closer to us in time than it is its cousin, Allosaurus,
from the Jurassic period.
So the great thing about dinosaurs is that they offer this tremendous vehicle to sort
of inject us into the flow of deep time.
>> This end of the dinosaur era, 65 million years ago,
we call it an extinction moment and do we now know how that was caused?
Was is the asteroid?
The Yucatan?
What's the latest theory?
>> There is still much debate over what killed off the dinosaurs.
It is almost a certainty now that a giant asteroid about ten kilometers across
slammed into the Gulf of Mexico.
Threw up a big cloud of gas and dust which enveloped the planet.
Blocked out sunlight for some indefinite period, stopping plants being able to
grow, therefore killing off herbivores and killing off carnivores.
If you were much bigger than about that,
you didn't survive on land through that major extinction event.
Having said that, there are other ideas out there.
There's this huge amount of volcanic activity that happens in India
called the Deccan Traps at right around the same time.
And the events of the vulcanism and the asteroid impact may be connected
we still haven't got the final word on that yet but
clearly there was a huge rock that hit the planet and threw it into cataclysm,
killing off on the order of sort of 60% of all the species around at that time.
>> Scott, there's been a number of mass extinctions, maybe six, and can you tell
us what caused them and what effect have they had on the history of life?
>> When it comes to mass extinctions,
we know about five that have happened in the past half billion years or so.
Before that we don't really have much of a record of complex life,
because there wasn't much complex life before that and
there weren't things that really fossilized.
But in that last 500 million years or
so there have been about five major mass extinctions which have wiped out
at least half of the living species on earth at that time.
These are basically biological bottle necks so that everything that survives has
to go through this extinction bottle neck and everything alive on earth today
is a direct descendant of the survivors of each of those mass extinction events.
So the last one was the one that killed off the dinosaurs 65 million years ago.
That's the fifth one and we are now in the middle of the sixth mass extinction.
This time around,
humans are the asteroid colliding with the planet that this extinction.
It's the first time it's driven by a single species, i.e., us.
Now that's an echo evolutionary experiment that
hasn't been run since the dinosaurs went extinct.
And we have to remember that we live in this inter-dependent web.
Now if we start pulling out all these threads in the web, things are going to
start to collapse and indeed that's all ready happening in some ecosystems.
So we need to learn from the dinosaurs.
We know that it take the earth, or at least the biosphere on the order
of five to ten million years recover from one of this mass death events.
So we have a chance to turn that around but
we need to act right now in order to do it.
Dinosaurs can help us understand not only things like mass extinctions but
global warming.
They lived in a time of global warming that
far exceeds the dire predictions of the present day.
North America throughout much of the Mesozoic was split into two line masses.
I mean, because of flooding by sea levels.
>> Can you give us a feel for how dinosaurs evolved, and what did they eat,
and did they change in size radically or rapidly?
Give us a sense of this millions of years of their evolution,
just a few of the periods.
>> Yeah, dinosaurs are known for being giants, and
most lineages of dinosaurs evolved giant forms,
things that completely blow away animals that live on land today.
I mean, 100-foot long, long-necked brontosaur type animals and
5,000 kilogram tyrannosaurs and things like that.
They started out, though, much more humbly and about sort of three feet tall,
little carnivores running around on their hind legs and it wasn't until
another extinction event wiped out a lot of the animals alive at that time.
That the dinosaurs that survived this extinction looked around and
saw all this ecological space and
then they exploded into it, evolving a lot of truly giant forms.
So from there, there's many herbivores, many carnivores,
some evolved feathers, and eventually, lead to the evolution of birds.
And it's to the point now where we really can't even separate dinosaurs and
birds, once we get down to that branching point.
Sometimes we find these things and we call them birds and
they turn out to be dinosaurs and vice versa.
So they truly did evolve,
lots of meat eating animals, lot's of plant eating animals.
And it looks like there was a number of omnivores eating plants and
meat, large bodied and small bodied.
So they were the dominant large bodied animals on land for
about 160 million years.
Mammals were there the whole time, didn't get much bigger than about that.
So the dinosaurs may have helped to keep them down, so to speak.
>> And what did the land look like?
And what were the trees and vegetation?
What were they eating if they were herbivores?
>> Dinosaurs lived in a hothouse world where there
many of the biomes that we know today didn't exist.
Grasslands weren't there.
Tropical rainforest weren't there.
Thunder wasn't there.
What was there?
We're not even sure, we're just beginning to reconstruct
the biomes that existed when the dinosaurs were around.
So we're piecing it together through finding fossil plants
in different places all over the world, the evolution of flowering plants,
the appearance of flowering plants occurred.
During the last period of the Mesozoic era, the crustaceous,
so Stegosaurus or Allosaurus never saw a flower.
Tyrannasorous rex and Triceratops did.
So flowers and dinosaurs co-evolved so now flowering plants
make up the vast bulk of all plants today throughout most of the Mesozoic era,
the age of dinosaurs, they weren't even around.
>> And more than nicely speaks of that moment when flowers
emerged around the world with this magic of color and so on.
And Richard Prum at Yale has been talking about birds and
reptiles having feathers, right?
>> Right, so
I remember being in a scientific meeting a number of years ago where people were
postulating that birds came directly from dinosaurs and the paleontologist said
I will not accept that idea until somebody shows me a dinosaur with feathers.
Sure enough about three months later,
somebody discovered a dinosaur fossil with feathers.
And now we have over a dozen feathered dinosaurs and
most of these have been found in an amazing site called Liaoning in China.
But it allows to say with some degree of certainty that many of the meat eating
dinosaurs that include the raptor dinosaurs, that include Tyrannosaurus Rex,
that include ostrich like dinosaurs had feathers.
>> You've talked about this evolution process is co-evolution.
Give us a feel for co-evolution of organisms but also ecosystems I presumed.
What is co-evolution?
>> Co-evolution is changing the one entity,
one biological entity affecting change in another biological entity.
So for example there's predator and prey.
A coyote and a rabbit.
If the rabbit evolves to be slightly faster forms.
In other words, if the faster rabbits tend to survive more than the slower rabbits
well all of a sudden the coyote is going to be getting faster to keep matching, and
so they're evolving together.
Pollinators and plants are another great example,
whether it's butterflies, bats, bees, all these different kinds of pollinators
interact with the plants such that the flowers are a siren song to animals.
These flowers, for example, that are bright red are targeting what humming
birds can see and they're pulling them in to do the job that the plant wants.
To spread around their genes and basically create more plants.
So there's all these different forms of evolution that involve the interplay of
different organisms and one can even make strong argument that all evolution
is co-evolution, it's all interdependent.
We tend to think of cause and
effect as A causing B, which in turn has an effect on C.
But that's really not how biology how life works when it changes.
It's much more of a grass roots pull themselves up by the bootstraps thing
where one thing changes another thing reacts and another thing reacts.
Whole ecosystems influence each other.
So anytime an entity changes it has affects that cascade throughout that
ecosystem.
>> And perhaps co-evolution has some implications for
us as humans evolving into the future as well.
Can you say anything about that?
>> A lot of people like to think that evolution has stopped.
That that was something that happened a long time ago.
But it hasn't, evolution is still going on all the time.
We are influencing it everyday in the decisions that we make and
behaviors that we undertake.
And so, the decisions we make today will influence evolution on the planet for
millions of years to come.
And one of the great things about the epic of evolution is that it
injects you into this sense of verticality.
We tend to live at this moment in time called the present.
>> Scott, this word evolution that you've used a lot and
clearly it applies to the life systems that you've described to us and
even the geological systems of Earth's emergence and we take it back into
the emergence of the cosmos and the human at the end of this huge process.
So how do you understand the importance of the word evolution?
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>> The word evolution is a problematic ones, there's a lot of argument around
this word and for most people evolution refers to the evolution of life but
I think it's important to expand the notion of evolution to refer to
the history of the universe.
That's how I like to define the term.
So it is cosmos, it is life and it is culture.
It's our story.
And why do I think that that's important?
Because this story is critical to our future, and by linking these things,
it shows that it's part of a single continuum.
So for example, most people think of evolution as the development of new forms.
It's what we would call diversification.
But if we look at the great story, the history of the universe,
we see an equal and opposite force, some people call unification.
So we have lots of atoms that form molecules,
molecules that form cells, and cells that form organisms.
So we have this emergence into some new form which is radically different.
That says another level of complexity and that's what we see in evolution.
We start with the simplest things basically radiation, and
then we get matter, and then galaxies.
And then, all these different things and finally including life in there.
And by showing that this is a continuum, it injects us,
humans, not only into the story of life but into the story of the universe and
I think that's the whole point of this great story is to see ourselves as
part of this grand narrative to inject a sense of meaning and
purpose into our lives that isn't there for a lot of people.
>> And would you say, as well, this story with both extinctions and
the new forms of life emerging?
For example, in the dinosaur extinction, isn't it the case that after that,
the mammalian forms of life were able to emerge?
Does that give us a sense that the creative and
more destructive processes are constantly intertwined?
What can we learn from that?
>> Yeah.
Over 99% of all species that have every exist are now extinct.
So extinction is one of the motors of evolution.
Things have to die out before new things can evolve.
People often talk about the extinction of the dinosaurs as opening the door for
mammals to become the dominant life forms ultimately leading to us.
And to my mind, this is true but trivial in the sense that mammals co-evolved with
dinosaurs for 160 million years, as did plants, as did insects, as did bacteria.
So it's not just the death of the dinosaurs that we have to thank,
it's the lives of the dinosaurs.
And we could make that same argument for
any major group of organisms in the history of life.
And so, I think that one of the key points here is that everything is intertwined and
whether it's an extinction or whether it's just this background of evolutionary
change overtime, all these things are intertwined.
And therefore the things that we do today are having this cascading
effect throughout the biosphere and we need to recognize that,
and channel our energy so that we can save as much as we can.
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