"I am become death, the destroyer of worlds."
said Oppenheimer, but of course… there may
have been a metazoan who said it first.
Sup Earthers, welcome back to DNews, I'm Trace.
Ahhhh, the metazoans, those early conquerors
and destroyers of Earth.
According to new research, these tiny animals
may have caused the first mass extinction
on planet Earth.
What a relief!
Humans are bad, you guys -- and are likely
causing another mass extinction right now
-- but c'mon, the metazoans did it first!
We're just johnny-come-latelys!
We're number six!
We're number six!!
Extinction is nothing new to our planet.
About 3.8 billion years ago life evolved,
but it wasn't super diverse; it was mostly
a blanket of gooey, single-celled, stationary
organisms.
Then, 600 million years ago, during what's
called the Cambrian explosion or Cambrian
Radiation, life began to diversify, and a
new, multicellular species evolved that was
unlike anything ever seen on Earth before:
The Metazoans.
The researchers called these, "ecosystem engineers."
They immediately began changing the environment
to suit their way of life.
Of course, at the time, there had already
been life for over 3 billion years… and
that old life wasn't cut-out for this new
world the metazoans were building.
During that Cambrian explosion, the older
animals were pushed out of the fossil record
as newer animals evolved legs, backbones,
complex eyes and the concept of predators
and prey which we still see today…
Thus, the first mass extinction began -- called
the End-Ordovician or Ordovician-Silurian
Event where 85-percent of species disappeared.
But this wasn't the only extinction.
Ohhh no!
Over the next 70 million years or so, these
new conquerors of the Earth enjoyed their
reign, another 70-percent would die in the
Late-Devonian extinction, about 360 million
years ago.
This was mostly in the ocean, with coral,
and other shallow-sea animals.
Hypothetically, they were hammered by changes
in sea levels, climate change, or perhaps
an asteroid impact.
But a major theory says modern-ish plants
may have evolved to suck more CO2 out of the
air, cooling the planet and causing an ice
age.
This extinction removed the famous trilobites
from the fossil record.
Stupid plants.
Then, 250 million years ago, more than 96
percent of the species that had evolved up
to that point were wiped from the fossil record
in what's called the Permian extinction -- or
the Great Dying.
During the Permian, there were synapsids -- sort
of a cross between dogs and lizards; picture
the fin-backed dimetrodon.
These pre-dinosaur Synapsids were one of the
first vertebrate kings of Earth.
Until this 3rd extinction -- where insects,
marine animals, and synapsids were devastated,
perhaps by an asteroid impact, acid rain caused
by pollution from massive volcanic activity,
or a sudden drop in oxygen caused by sea-organisms
affecting the atmosphere.
Again plants and animals still killing each
other.
The fourth Triassic-Jurassic extinction started
200 millions years ago, and since the loss
of all that marine life after the Permian,
cephalopods exploded onto the scene to fill
the now-empty space.
During this event, more marine mammals were
wiped out, the reef-building coral that had
spent hundreds of millions of years recovering
was hit again, and these Knights of Summer,
the cephalopods, were hit hard.
The synapsids that survived, evolved into
dinosaurs, but then were hit by the famous
K/T extinction event that wiped them out too,
65 million years ago.
Though we were already in trouble with sea-level
rise and eruptions increasing around the planet,
so that meteor just accelerated the fifth
extinction that was already in progress.
This killed another three-quarters of the
species including: dinosaurs, flying pterosaurs,
ammonites, flowering plants, and a few others…
Damn.
Today, everything that exists evolved from
the survivors of each of these events, and
some scientists believe humans have kicked
off another mass extinction, the Holocene
or Anthropocene extinction event.
The sea-levels are rising, atmosphere and
soil are changing, and many of the world's
species are disappearing.
Knowing about these other extinctions… all
this sounds familiar, but only time will tell
if we're in a Sixth Mass Extinction.
And in geologic time, we'll have a long wait.
But we can rest easy knowing the metazoans
started it, right?
Though I guess, we are technically multicellular
ancestors of the metazoans technically…
so *gulp*
Look, we don't have to freak out too much.
Maybe there's a way to stop this sixth mass
extinction.
Will and Julia came up with some strategies,
right here.
There was a 
lot to cover in this video, should we do an
extinction week where we look at each event
on it's own?
What do you think?
