[MUSIC PLAYING]
ANTHONY BARNOSKY: Species do not last forever.
You can think of species a lot like you
think of a human lifetime.
They have a beginning and they have an end.
SPEAKER 1: Anthony Barnosky and Kaitlin Maguire
are paleobiologists.
In their search for a better understanding of today's world,
they study animals that haven't walked
the Earth in millions of years.
ANTHONY BARNOSKY: The big focus of my research
is trying to understand what is the normal background
rate of extinction.
That is, what is the normal pace of species origination
and extinction.
It's really important to understand
the normal or background rate of extinction
because without that, you have no basis of comparison
for knowing whether or not the number of extinctions
we're seeing today are too many or not.
KAITLIN MAGUIRE: The oreodont skeleton's right over that way.
ANTHONY BARNOSKY: Right over there?
KAITLIN MAGUIRE: Yep.
SPEAKER 1: Barnosky and Maguire are here
in eastern Oregon's John Day Fossil Beds National
Monument with a special permit to search
for fossils of ancient mammals.
ANTHONY BARNOSKY: We've just come across an oreodont
And oreodonts are a completely extinct group of mammals.
Their body form looks sort of like a deer and sort of
like a pig, if you can imagine that mixture.
That's part of an oreodont spine.
We have part of a leg bone, the shin.
We see little bits and pieces of bone,
so it looks like there's most of an oreodont skeleton buried
in this hillside.
SPEAKER 1: By studying fossils like this,
the team is gathering data.
Data that will help them determine
when the species first appeared and when they disappeared.
And by collecting these data for many species,
they can calculate how often extinctions normally occurred.
ANTHONY BARNOSKY: The John Day Fossil Beds
are a really special place for doing
the sorts of research I do.
Here we have the longest record of mammalian evolution
and extinction in a single place anywhere in North America.
SPEAKER 1: The strata of rock here
were formed over tens of millions of years.
They accumulated as layer after layer of volcanic ash and other
sediments were slowly deposited, one on top of the other.
ANTHONY BARNOSKY: If you look at some of the formations
around here, for example, Blue Basin
goes from about 31 million years old to about 28
and 1/2 million years old.
On the other hand, Sheep Rock is a little bit younger,
ultimately.
It starts at about 29 million years old
and goes up to as young as 25 million years old.
And from the Mascall Overlook, you
can see even a younger sequence of rocks running from about 16
million to 7 million years old.
So if you put all of those three sets of exposures together,
we're going from slightly older than 30 million years,
all the way up to 7 million years.
And it's arranged in essentially three separate chapters.
SPEAKER 1: These chapters of time
contain both the origins and extinctions
of many species of mammals, including oreodonts.
KAITLIN MAGUIRE: We know that this specimen
is about 29 million years old because of where it's found.
So it is above certain layers that we
know are older at 30 million and then it's
below some of the other layers, which we know are much younger.
SPEAKER 1: The team wraps the oreodont specimen
in a plastered jacket for transport
back to the lab for more precise identification.
Maguire takes samples of compressed volcanic ash
near where they found the specimen.
This volcanic rock contains microscopic zircon crystals,
which can be radiometrically dated
to determine accurate ages of the rock layers
and the specimens near them.
KAITLIN MAGUIRE: With zircon dating,
we can get within 10,000 years, which
is a phenomenally short range span for the fossil record.
And these methods that they're using today are new.
And we've never before had this precision in dating rocks.
SPEAKER 1: In the paleontology lab at John Day Fossil Beds,
scientists work to identify the exact species that
was buried in these layers.
KAITLIN MAGUIRE: We use teeth to identify mammalian species.
First of all, because they preserve really
well in the fossil record.
And second of all, they have distinct morphological features
or shapes to them that are specific for each species.
SPEAKER 1: It turns out that the oreodont Maguire and Barnosky
uncovered is in the species Eporeodon occidentalis
and lived around 28.8 million years ago.
This, and specimens of other oreodont species,
tell us that oreodonts first appeared here
about 48 million years ago and went extinct
about 5 million years ago.
But that's only part of the picture.
The specimen's details can now be
added to a database containing millions of fossils
from thousands of species across the globe.
ANTHONY BARNOSKY: Over the past couple of hundred years,
we have now accumulated literally millions of specimens
in museums.
And at this point, paleontologists
have identified over 12,000 species.
All of that information is now in computerized databases. .
We can go to those and we can actually,
for each one of those 12,000 species,
say, when was the first occurrence?
When was the last occurrence?
Knowing that information for thousands of species,
we can then calculate out the overall background extinction
rate for mammals as a whole.
All we're really trying to do is say,
if we had a million species out there on the landscape,
how many of those would we expect
to see going extinct in a year?
And we call that measure extinctions
per million species years.
SPEAKER 1: Barnosky's analysis has
revealed that for mammals the background rate of extinction
is about two extinctions per million species years.
If we apply this background extinction
rate to be approximately 5,500 species of mammals on Earth
today, we would expect one mammal species
to disappear every 100 years.
ANTHONY BARNOSKY: And what we found
is that species in the past 100 years have been going extinct
somewhere between 28 to 67 times too fast.
SPEAKER 1: It's a daunting conclusion.
Species are going extinct way too quickly.
Does this mean we're headed for the Sixth mass extinction?
ANTHONY BARNOSKY: All that stands between us and the Sixth
mass extinction are keeping those threatened
an endangered species on Earth.
If we did not do that, within as little as three centuries
you would lose three out of four of every species
you're familiar with.
SPEAKER 1: And once species are gone, they cannot be recovered.
That biodiversity is lost forever.
ANTHONY BARNOSKY: The bad news, obviously,
is that the rates of extinction that are going on today
are way, way too fast.
The good news is most of what we want to save
is still out there to be saved.
All we have to do is step up the conservation efforts
that we already know how to do.
We have the Sixth mass extinction looming.
We know what's causing it.
We know how to fix it.
All we have to do is fix it.