The 5 Worst Mass Extinctions in History

Summary

This 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

00:00

🌍 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.

05:02

🗓 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.

10:02

🦕 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.

Keywords

💡Mass Extinction

Mass extinction refers to a phenomenon in Earth's history where a significant proportion of species on the planet are wiped out in a relatively short geological time frame. It is central to the video's theme, illustrating the catastrophic events that have shaped the planet's biodiversity. The script mentions five major mass extinction events, each resulting in the loss of over 50% of species, including the 'Great Dying' during the Permian-Triassic extinction, which wiped out 95% of species.

💡Ordovician-Silurian Extinction Event

The Ordovician-Silurian extinction event is one of the five major mass extinctions discussed in the script. It occurred around 450 million years ago and is characterized by two dramatic die-offs, likely caused by glaciation and drops in sea level. This event is significant as it resulted in the extinction of 27% of marine families and 60% of marine genera, highlighting the impact of climate change on biodiversity.

💡Devonian Extinctions

The Devonian extinctions, occurring around 360 million years ago, represent a prolonged series of mass extinctions that spanned a period of 500,000 to 25 million years. The script describes this as a challenging event to time-stamp, with multiple pulses of extinction, affecting both marine and terrestrial life. This keyword is important as it exemplifies the ongoing struggle of species to adapt to rapid climate changes.

💡Permian-Triassic Extinction Event

Known as 'The Great Dying,' the Permian-Triassic extinction event is the most severe mass extinction discussed in the script, occurring about 250 million years ago. It led to the extinction of 53% of marine families, 84% of marine genera, 70% of land species, and 95% of marine species. The video attributes this event to a combination of catastrophic events, including volcanic eruptions and the release of gases from methane hydrate reservoirs, emphasizing the profound impact of environmental changes on life.

💡Triassic-Jurassic Extinction Event

The Triassic-Jurassic extinction event, around 200 million years ago, is another significant mass extinction highlighted in the script. It resulted in the death of most early land animals, including large amphibians and archosaurs, paving the way for the dinosaurs. This keyword is relevant as it marks a transition in Earth's history, showing how mass extinctions can lead to evolutionary shifts.

💡Cretaceous-Tertiary Extinction

The Cretaceous-Tertiary extinction, also known as the KT extinction, is the most recent of the mass extinctions mentioned in the script, occurring about 65 million years ago. It is famous for the extinction of non-avian dinosaurs and is widely believed to have been triggered by a massive asteroid impact. This event signifies the end of the Mesozoic Era and the rise of mammals and birds, illustrating the transformative power of mass extinctions on the course of evolution.

💡Climate Change

Climate change is a recurring theme in the script, often linked to the causes of mass extinctions. It is defined as significant changes in global temperature and weather patterns over time. The video suggests that climate change, often caused by shifting CO2 levels, is a common factor in mass extinction events, including the current discussions on the potential sixth mass extinction.

💡Hypernova

A hypernova, as mentioned in the script, is an explosion of a star that is 100 to 300 times the size of the sun. The Ordovician event is theorized to have been potentially triggered by a gamma-ray burst from a hypernova, which could have devastated Earth's ozone layer and led to mass extinction. This keyword is crucial as it introduces an extraterrestrial factor that can influence Earth's biodiversity.

💡Marine Anoxia

Marine anoxia refers to a depletion of oxygen in ocean waters, which can lead to the extinction of marine species that depend on oxygen to survive. The script discusses how this phenomenon occurred during the Devonian extinctions, contributing to the loss of marine life. This keyword is important for understanding how changes in oceanic conditions can drive mass extinctions.

💡Habitat Destruction

Habitat destruction is a key factor in the current discussions on the potential sixth mass extinction, as mentioned in the script. It involves the loss or degradation of natural environments where species live, often due to human activities. The video points out that habitat destruction, along with rising CO2 levels, pollution, and overharvesting, is driving current extinction rates to unprecedented levels.

💡Biological Classification System

The biological classification system is a method of organizing and naming organisms based on their evolutionary relationships. The script uses this system to discuss the scale of the Ordovician-Silurian extinction event, noting the percentages of families and genera that went extinct. This keyword is important for understanding the taxonomic context of mass extinction events and the scale of biodiversity loss.

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