The 5 Worst Mass Extinctions in History
Summary
TLDRThis script delves into the history of mass extinctions on Earth, highlighting five major events that wiped out a significant portion of species. It discusses the causes, such as climate change and asteroid impacts, and draws a parallel to current human-induced extinction rates, suggesting we may be in the midst of a sixth mass extinction. The script educates viewers on the biological classification system and the impact of past events on marine and land life, ending with a call to action for ideas on naming the potential ongoing extinction.
Takeaways
- 🌏 The Earth has experienced five mass extinctions in the last 450 million years, each defined by the extinction of at least 50% of the planet's species.
- 🦠 The 'Great Dying' during the Permian-Triassic extinction event wiped out more than 95% of all species, marking the most severe mass extinction.
- 😷 The speaker humorously suggests wearing a gas mask, but acknowledges it might be excessive or useless in the face of a mass extinction event like a meteor strike.
- ❄️ Mass extinctions are often linked to rapid climate change, typically caused by shifts in CO2 levels and global temperature fluctuations.
- 🌡️ Current extinction rates, influenced heavily by human activity, are 100 to 1000 times higher than natural rates, rivaling the intensity of past mass extinction events.
- 🦈 The Ordovician-Silurian mass extinction was marked by two significant die-offs related to glaciation and drops in sea level, heavily impacting marine life.
- 🌊 The Late Devonian extinctions were characterized by a series of pulses over millions of years, affecting both marine and terrestrial life, possibly due to asteroid impacts or volcanic activity.
- 🔥 The Permian-Triassic extinction, or 'Great Dying,' may have been triggered by a comet or asteroid, followed by volcanic eruptions in Siberia that drastically altered global temperatures.
- 🦕 The Triassic-Jurassic extinction event led to the demise of many early land animals and large amphibians, paving the way for the dinosaurs to dominate.
- 💥 The Cretaceous-Tertiary extinction, marked by an asteroid impact, resulted in the extinction of non-avian dinosaurs and allowed mammals and birds to thrive.
- 🌱 Some theorize that the Devonian extinction event might have been caused by plants absorbing excessive CO2, leading to global cooling and mass extinction.
Q & A
What is the definition of a mass extinction event?
-A mass extinction event is defined as a period when at least 50 percent of the species on the planet go extinct.
How many mass extinction events have occurred in the last 450 million years?
-There have been five mass extinction events in the last 450 million years.
What is the term used for the most severe mass extinction event in Earth's history?
-The most severe mass extinction event is referred to as 'The Great Dying.'
What percentage of species were wiped out during 'The Great Dying'?
-More than 95 percent of the species on the planet were wiped out during 'The Great Dying.'
What common factors are associated with the five major mass extinction events?
-Climate change, usually caused by changing CO2 levels and relatively rapid global temperature changes, are common factors associated with the five major mass extinction events.
How do current extinction rates compare to natural rates due to human influence?
-Current extinction rates are between 100 and 1,000 times what they would be naturally due to human activities.
What was the Ordovician-Silurian mass extinction event, and what caused it?
-The Ordovician-Silurian mass extinction event occurred 450 million years ago and was characterized by two dramatic die-offs involving the influx of gigantic glaciers and dramatic worldwide falls in sea level.
What is the biological classification system used to categorize life on Earth?
-The biological classification system classifies all life based on common descent, starting with the most specific (species) and getting to the most general (domain and life).
What was the Late Devonian extinctions, and what were its effects on life?
-The Late Devonian extinctions occurred 360 million years ago and were a prolonged series of mass extinctions that affected both marine and land life, with half of all genera and 70 percent of all species going extinct.
What is the Permian-Triassic extinction event, also known as 'The Great Dying', and what were its consequences?
-The Permian-Triassic extinction event, also known as 'The Great Dying', occurred about 250 million years ago and was so destructive that it remains the only known mass extinction of insects, leading to the extinction of 53 percent of marine families, 84 percent of marine genera, 70 percent of land species, and 95 percent of marine species.
What is the current hypothesis regarding the cause of the Triassic-Jurassic extinction event?
-The Triassic-Jurassic extinction event, which occurred 200 million years ago, is thought to have been caused by a combination of factors, including a possible comet or asteroid impact and subsequent volcanic eruptions in the Siberian Traps, leading to an increase in global temperatures.
What is the Cretaceous-Tertiary extinction event, and what is its significance?
-The Cretaceous-Tertiary extinction event, also known as the KT extinction, occurred about 65 million years ago when a giant asteroid or comet struck Earth, leading to the extinction of non-avian dinosaurs and paving the way for the age of mammals and birds.
What are the current human-induced factors contributing to the potential sixth mass extinction event?
-The current human-induced factors contributing to a potential sixth mass extinction event include rising CO2 levels, habitat destruction, invasive species, pollution, and overharvesting.
What is the normal extinction rate for our planet, and how does it compare to the current rate?
-The normal extinction rate for our planet is about 10 to 25 species per year, whereas the current rate is about 100 times that, indicating a significant human impact on biodiversity.
Outlines
🌍 The Reality of Mass Extinctions
This paragraph introduces the concept of mass extinctions with a humorous yet informative approach, discussing the speaker's preparedness for a potential future event. It highlights the gravity of mass extinctions, defined as the loss of at least 50% of the planet's species, and references the 'Great Dying' that wiped out over 95% of species. The script also touches on the possibility of the Earth currently experiencing a sixth mass extinction, potentially influenced by human activity and climate change, and invites viewers to explore the history of mass extinction events.
🗓 A Journey Through Time: Mass Extinctions Past
This paragraph delves into the history of mass extinctions, starting with the Ordovician-Silurian event 450 million years ago, characterized by dramatic sea level drops and glaciation, leading to significant marine life extinction. It then moves to the Late Devonian extinctions, which affected both marine and land life, possibly due to global cooling caused by plant life absorbing CO2. The paragraph culminates with the Permian-Triassic extinction event, known as 'The Great Dying,' which was catastrophic for insects and land species, and may have been triggered by a combination of events including volcanic eruptions and the release of gases from methane hydrate reservoirs.
🦕 The Last Great Extinction and Its Aftermath
The final paragraph discusses the most well-known mass extinction, the Cretaceous-Tertiary event that led to the demise of non-avian dinosaurs and allowed mammals and birds to thrive. It mentions the leading theory of an asteroid impact, as well as the concurrent volcanic activity in India that may have caused global warming. The script concludes by connecting past extinctions to current concerns, suggesting that human activities such as habitat destruction and pollution might be driving a sixth mass extinction at an unprecedented rate, and invites viewers to consider the implications and potential names for this event.
Mindmap
Keywords
💡Mass Extinction
💡Ordovician-Silurian Extinction Event
💡Devonian Extinctions
💡Permian-Triassic Extinction Event
💡Triassic-Jurassic Extinction Event
💡Cretaceous-Tertiary Extinction
💡Climate Change
💡Hypernova
💡Marine Anoxia
💡Habitat Destruction
💡Biological Classification System
Highlights
The speaker humorously prepares for a potential mass extinction event, suggesting the need for awareness and preparedness.
There have been five mass extinctions in the last 450 million years, each with significant impacts on biodiversity.
A mass extinction is defined as the extinction of at least 50% of the planet's species.
The 'Great Dying' during the Permian-Triassic extinction event wiped out more than 95% of all species.
Mass extinctions are often linked to rapid climate change, usually caused by shifting CO2 levels.
The possibility of a sixth mass extinction event is not far-fetched, given current environmental trends.
Human activities have already increased extinction rates to between 100 and 1000 times the natural rate.
The Ordovician-Silurian mass extinction was marked by two dramatic die-offs due to glacial influx and sea level drops.
Gondwana's movement into the polar region during the Ordovician event led to a significant temperature drop and increased glaciation.
A gamma-ray burst from a hypernova could potentially cause mass extinction through ozone layer destruction.
The Late Devonian extinctions were characterized by a series of pulses over a period of 500,000 to 25 million years.
Plants may have contributed to the Late Devonian mass extinction by absorbing excessive CO2 and causing global cooling.
The Permian-Triassic extinction, also known as the 'Great Dying,' was the only event to affect insects and had a profound evolutionary impact.
Volcanic eruptions in the Siberian Traps and methane hydrate releases are believed to have caused the 'Great Dying.'
The Triassic-Jurassic extinction paved the way for the age of dinosaurs, despite the loss of many early land animals.
The Cretaceous-Tertiary extinction, triggered by an asteroid impact, marked the end of non-avian dinosaurs.
Current extinction rates are 100 times the natural rate, largely due to human activities such as habitat destruction and pollution.
The speaker invites viewers to propose names for a potential sixth mass extinction event in the comments section.
Transcripts
hello there uh i may look strange to you
but i like to be prepared at all times
for whenever the next mass extinction
might happen but i do think it's
important to impart this information in
a non-muffled way so i think i'm just
gonna go ahead and take this off
ah that would suck to have to wear that
all the time so you never know when the
next mass extinction is going to happen
i mean there have been five of them in
the last 450 million years alone and
it's not like a mass extinction is some
kind of blurry ill-defined term it's
when at least 50 percent of the species
on the planet go extinct one of them
which has been aptly dubbed the great
dying wiped out more than 95
of the species on the planet it's enough
to make you walk around with a gas mask
[Music]
it's possible that the gas mask is
excessive it's also possible that it's
useless i mean if we get hit by a big
meteor probably not going to help that
much mass extinction events happen
pretty fast in a geological scale but
the actual like dying occurs on our
scale quite slowly tens of thousands of
years and of course the most important
thing to look at here is what these five
giant mass extinction events had in
common so that we can see them coming
climate change usually caused by
changing co2 levels and relatively rapid
global temperature changes yeah so you
see where i'm going with this i don't
mean to alarm anyone here but the idea
that the earth is currently as i sit
here going through a sixth mass
extinction event is
actually not that crazy scientifically
it actually might make really good sense
before we even look at climate change we
already know that humans have been a
strange and mysterious and new force for
mass extinction current extinction rates
are somewhere between 100 and a thousand
times what they would be naturally due
to humanity's
very enterprising nature and that rate
is similar to or even greater than the
rates of some mass extinction events of
the past so let's forget about all the
depressing stuff for a moment and hop
into the scishow time machine our first
stop 450 million years in the past and
we're gonna get a little bit wet because
pretty much all life on earth at that
time was in the ocean welcome everyone
to the ordovician seluvian mass
extinction event now you're not going to
see any giant comets meteors falling
from the sky but sometime in the next 10
million years or so we're going to see
two really dramatic die-offs both of
them involving the influx of gigantic
glaciers and dramatic worldwide falls in
sea level these two events will be
separated by about one million years as
geologic time remember people and by the
end of the second one 27 of all marine
families and 60
of all marine genera were extinct and i
can tell from your blank stares that
we're going to require a little bit of a
refresher on the biological
classification system which of course
classifies all life based on common
descent and which we will be talking a
lot about as we get more into extinction
events starting with the most specific
and then getting to the most general we
have species genus family order class
phylum kingdom domain and good old life
back to the ordovician event what
scientists think happened here was that
gondwana one of the two supercontinents
at the time moved into the polar region
this set off a huge drop in temperature
also a huge increase in glacial
formation which dropped sea levels
marine invertebrates were the hardest
hit two-thirds of all the brachiopod and
bryozoan families disappeared it was
also a tough time to be a bivalve or a
trilobite and just because i find this
fascinating there's also another theory
about what may have happened to cause
the ordovician event a gamma-ray burst
from a hypernova somewhere within 6 000
light years of earth a supernova that's
when a star explodes a hypernova is when
a star that's like 100 to 300 times the
size of the sun explodes even like 10
seconds of a gamma-ray burst from a
hypernova would completely destroy the
ozone layer and dose everything on earth
with a nice healthy amount of uv
radiation when i say healthy i mean
unhealthy all right everybody back in
the time machine we're going ahead 100
million years to 360 million years ago
to the late devonian extinctions this is
the beginning of a prolonged series of
mass extinctions in which half of all
genera and 70 of all species will go
bye-bye marine life will once again be
hit very hard but so will the spiders
and the scorpions and the
proto-amphibians which are just taking
their first steps out on the land
narrowing down a time frame for this
event has been difficult scientists can
only say that over a period of 500 000
to 25 million years that's a big gap
there i know there were a series of
extinction pulses each lasting about 100
000 years no gamma ray bursts are
suspected here this is once again being
caused by a global drop drop-off in
temperatures people aren't sure what
caused it probably either an asteroid
impact or a giant super volcano each of
those things would have released massive
amounts of dust or ash into the
atmosphere drastically changing the
climate glaciers probably once again
inundated gondwana what we also know is
that ocean levels fell and lost most of
their oxygen in the process in what's
called ocean and noxia some believe that
temperatures in the steaming seas of the
devonian fell from 93 to about 78
degrees coral reefs were hit so hard
that it would be a hundred million years
before they recovered but there's
another interesting theory here and
that's that plants which were for the
first time really taking hold on land or
absorbing so much carbon dioxide from
the atmosphere that they actually caused
global cooling so in fact plants were
responsible for that mass extinction
event how could you and now we will
travel to the big one also known as the
permian triassic extinction event also
known as the great dying it is now about
250 million years ago and a combination
of catastrophic events is about to
totally alter life on planet earth so
destructive is this event that it
remains the only known mass extinction
of insects this may have been triggered
by a comet or asteroid impact but what
scientists feel fairly certain about is
that a subsequent volcanic eruption in
an area known as the siberian traps was
responsible for an increase in global
temperatures of 5 to 10 degrees these
volcanic eruptions covered an area
roughly the size of western europe and
they lasted for a million years but then
it got worse the sudden release of gases
from methane hydrate reservoirs below
the seafloor possibly caused by
underwater volcanic activity decimated
the seas leading to periods of too much
oxygen called hyperoxia and too little
oxygen the return of anoxia and marine
life does not fare well in either of
these conditions these two events at
least possibly others led to a shift in
ocean currents and general inhospitable
environment for most of the earth
species when the die-off was finally
finished 53 of marine families 84 of
marine genera 70 of land species and 95
of marine species were extinct the
permian extinction had an enormous
evolutionary effect taking place just as
mammal-like reptiles like pelicosaurs
and thyrapsids were in their prime it
would be more than 30 million years
before these vertebrates and the earth
in general would recover but it did
recover until 200 million years ago when
the triassic jurassic extinction killed
off many early land animals this
includes the death of most of the
thoraxids large amphibians and the
archosaurs paving the way for the age of
the dinosaurs scientists probably know
less about this mass extinction event
than any other but what is known is that
23 of families and 48 percent of genera
went extinct but what was left fairly
untouched were plants and dinosaurs
which now had a lot less competition
this was roughly the time when the
massive supercontinent known as pangaea
was breaking apart due to volcanic
eruptions and the massive release of
carbon dioxide from those eruptions may
have caused some pretty intense global
warming again species don't fare well
when temperatures increase quickly like
this and it wouldn't be an extinction
event without scientists wondering about
whether or not there was a massive
impact of some kind but so far nobody's
found any likely crater candidates do
you know where there is evidence of an
impact crater right off the coast of
mexico's yucatan peninsula and you've
heard of this one it's where a giant
asteroid or comet struck about 65
million years ago and that kicked off
the cretaceous tertiary extinction you
know this one it's the one that killed
off all the non-avian dinosaurs and
ushered in the glorious age of mammals
and birds mammals and birds the kt
extinction as it's also known killed off
half of all genera and 75
of species and while the giant asteroid
impact winter theory is the leading one
it's by no means the only one also
happening at the same time there was a
giant uh volcanic eruption in india that
may have caused massive global warming
and that final extinction event brings
us back around to today where 99 of the
species that have ever existed on this
planet are extinct but we
aren't
we are the one percent not lucky for us
in the history of humanity we haven't
had to deal with any giant comet strikes
or super volcanoes but we do have to
deal with a possibly equally destructive
force
each other some scientists think that we
are already in the middle of an event
that's moving faster than the kt
extinction but instead of being driven
by continents or volcanic eruptions
these extinctions are being caused by
rising co2 levels habitat destruction
invasive species pollution and over
harvesting we already know what changes
in global temperature can do to a planet
click over here for uh information on on
that in our climate change video a
normal extinction rate for our planet is
about 10 to 25 species per year and
we're already doing about 100 times that
so clearly the seven billion of us here
on this planet are having a pretty big
impact i guess the question that remains
for us to answer is what are we going to
call the sixth mass extinction event and
i would love for you to leave ideas for
that in the comments thank you for
watching of course uh there's sources
for all of our information down in the
description because we are scientists
here we
we do
it's hard to breathe we are around if
you have questions or suggestions on
facebook twitter and of course in the
youtube comments below and if you want
to continue to be smarter and know more
about the world go to youtube.com
scishow and subscribe
goodbye
[Music]
you
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