Five Great Dyings

Prologue · 445 → 201 million years ago

Five times life nearly ended

Species go extinct all the time. A mass extinction is different: the extinction rate spikes so high that most species disappear within tens to hundreds of thousands of years. The globe on the left rewinds from today to where the continents sat during each crisis.

Bars show the range of published estimates for marine species lost. These figures are extrapolated from genus and family counts, not counted directly. The end-Cretaceous event is shown in grey for comparison.

Where “the Big Five” comes from

In 1982 Raup and Sepkoski counted how many families of marine animals disappeared in each interval of the fossil record and found five that stood out. A 2023 review argues that the five are the extreme tail of a continuum rather than a separate class of event.

The end-Guadalupian (Capitanian) crisis, about 259.5 million years ago, used to be lumped in with the end-Permian. Some researchers now rank it as a sixth mass extinction; others see a gradual decline or a regional crisis. Chapter III covers the debate.

How to use: pick a chapter below the globe or press ← → to change step · ▶ plays the step · drag to rotate the globe · “Play the film” runs every step full-screen.

Sources: Raup & Sepkoski 1982 (Science); Marshall 2023 (Cambridge Prisms: Extinction); Stanley 2016 (PNAS)

Chapter I · Step 1 · ~445 million years ago

A world where life lived in the sea

In the Late Ordovician, tropical sea surfaces ran at roughly 32–37 °C. Sea level was high and shallow seas flooded the continental margins. Marine animals had just gone through their greatest diversification so far. On land there were only small moss-like plants in places; most of it was bare rock.

Tropical sea surface

32–37 °C

From oxygen isotopes in fossils (Finnegan et al. 2011)

Life on land

Almost none

Early moss-like plants; no trees and no land animals

Where the South Pole was

Central Gondwana, under today’s Sahara

Glacial scratches from this ice age can still be seen in the deserts of Algeria and Libya

Typical sea life

Trilobites Orthocone nautiloids Graptolites Brachiopods Bryozoans Crinoids Tabulate corals Conodonts

The globe uses the Scotese & Wright (2018) palaeo-elevation model (PaleoDEM) for 445 million years ago. Land and vegetation colours are an artistic interpretation based on latitude and distance from the coast.

Sources: Finnegan et al. 2011 (Science); Scotese & Wright 2018 PALEOMAP PaleoDEMs

Chapter I · Step 2 · ~444 million years ago · first pulse

A sudden ice age

This is the only Big Five extinction tied to an ice age. A vast ice sheet formed on Gondwana near the South Pole. Water locked into ice drained the shallow shelf seas where most marine life lived.

1. CO₂ falls, perhaps from faster rock weathering that some studies link to early land plants (a hypothesis)
2. An ice sheet spreads across Gondwana over the South Pole
3. Sea level falls about 100 m; shallow seas drain and habitat disappears
4. Tropical seas cool about 5 °C; warm-water animals die

Ice volume

~150 million km³

Plausible range 50–250 million km³

Sea level

down ~100 m

Brenchley et al. 1994

Tropical seas

~5 °C cooler

Finnegan et al. 2011

Glacial maximum

~200,000 yr

U-Pb dates from south-west China (Ling et al. 2019)

In this scene, shelf seas shallower than 100 m on the PaleoDEM turn into pale exposed land. Shelf depths in ancient maps are estimates, so the picture shows the trend rather than an exact coastline.

Sources: Finnegan et al. 2011 (Science); Ling et al. 2019 (Solid Earth Sciences); Armstrong & Harper 2014 (GSA Special Paper 505)

Chapter I · Step 3 · ~443 million years ago · second pulse

Meltwater and suffocating seas

When the ice melted, sea level rose again, but the water that flooded the shelves was warm and low in oxygen, in places laced with hydrogen sulphide. Animals that had adjusted to the cold died in the second pulse. Low-oxygen conditions lingered in some regions for more than 3 million years into the Silurian.

Species lost

~85%

Harper et al. 2014; Bond & Grasby 2020

Genera lost

42–57%

Depending on method (Stanley 2016 to Bambach 2006)

Rank

Second-largest (by genera)

Behind only the end-Permian (Stanley 2016)

Hit hard

Trilobites ~70% of genera Crinoids ~70% of genera Deep-water graptolites Brachiopods Bryozoans Conodonts

Survivors and winners

Cold-water Hirnantia brachiopods Graptolites that radiated in the Silurian

Debate: the classic model blames the ice age. Bond & Grasby (2020) found mercury and metal anomalies at Dob’s Linn, Scotland, and proposed that massive volcanism may have been the trigger, but no lava province of this age has been found and a published rebuttal followed.

Recovery took about 5 million years into the Silurian, far faster than after the end-Permian.

Sources: Bond & Grasby 2020 (Geology); Stockey et al. 2020 (Nature Communications); Stanley 2016 (PNAS); Sheehan 2001 (Annu. Rev. Earth Planet. Sci.)

Chapter II · Step 4 · ~375 million years ago

The first forests

The Devonian saw the first true trees. Archaeopteris had woody trunks and deep roots, and forests spread from the coasts into the interior. In the sea, reefs built by stromatoporoid sponges and rugose corals reached the greatest extent in Earth’s history, and armoured fish (placoderms) ruled the water.

Tropical sea surface

~30–32 °C

Joachimski et al. 2009

Dunkleosteus

~4 m

A 2023 re-estimate; older figures said 6–10 m

Reef builders

Stromatoporoid sponges, tabulate and rugose corals

Not the same groups as today’s reef corals

In this scene, the green spreading inland from the coasts stands for expanding forests. The interior of Euramerica stays dry, which is where the Old Red Sandstone of Europe and North America comes from.

Sources: Algeo & Scheckler 1998 (Phil. Trans. R. Soc. B); Joachimski et al. 2009 (EPSL); Engelman 2023 (Diversity)

Chapter II · Step 5 · 372.7 → 371.9 million years ago

The Kellwasser event

The Late Devonian was not a single event but a series of crises spread over millions of years. The severe one is the Kellwasser event, named after a valley in the Harz Mountains of Germany where two black shale layers record it.

1. Spreading forests speed up weathering; nutrients wash into the sea (hypothesis)
2. Algae bloom, die and decay, consuming the oxygen in the water
3. Water goes anoxic, leaving two black shale layers
4. Buried organic carbon draws down CO₂, and the climate cools in pulses

Boundary age

371.87 Ma

±0.11 Myr (Da Silva et al. 2020)

Two pulses

~90 + ~110 kyr

About 800,000 years apart, paced by Earth’s orbit

Tropical cooling

5–7 °C

Two episodes (Joachimski & Buggisch 2002)

Viluy volcanism

Possible trigger

Eastern Siberia; mercury anomalies at the boundary in South China

Hit hard

Stromatoporoid sponges Tabulate and rugose corals 3 trilobite orders ~Half of placoderm families Atrypid brachiopods

Reefs afterwards

Large animal-built reefs did not return to their former extent until the Mesozoic.

Sources: Da Silva et al. 2020 (Scientific Reports); Zhang et al. 2021 (Frontiers in Earth Science); Joachimski & Buggisch 2002 (Geology)

Chapter II · Step 6 · ~359 million years ago

The Hangenberg event

The Devonian closed with a short, sharp crisis that hit vertebrates hardest. Glaciers formed on Gondwana (glacial deposits survive in Brazil and Bolivia), sea level fell more than 100 m, and then oxygen-starved water spread through the oceans.

Duration

~50 kyr

Myrow et al. 2014

Sea level

down >100 m

Evidence from Morocco

Vertebrates

~96% of species

Lost in this interval (Sallan & Coates 2010)

The Late Devonian as a whole

Species lost

~40–75%

The widest disagreement of all five events

Genera lost

16–50%

Low figure from Stanley 2016, high from McGhee et al. 2013

Gone

All placoderms Dunkleosteus Phacopid trilobites Ammonoids ~87% of species

Survivors

Ray-finned fish Sharks (small for a long time) Early tetrapods Crinoids

Debate: the ultraviolet hypothesis (Marshall et al. 2020) rests on malformed spores from East Greenland and Bolivia. It has been criticised (Racki 2021) and remains unresolved.

Sources: Marshall et al. 2020 (Science Advances); Myrow et al. 2014 (Terra Nova); Sallan & Coates 2010 (PNAS); Stanley 2016 (PNAS)

Chapter III · Step 7 · ~262 million years ago

The age of the dinocephalians

By the Middle Permian, Pangaea was almost complete and its interior was arid. On land, therapsids (the lineage that leads to mammals) dominated. Dinocephalians were the largest land animals of their time.

Typical land animal

Dinocephalians

Such as Moschops, with a skull thick as a helmet

Typical sea life

Fusulinids

Single-celled foraminifera the size of a rice grain or larger

Key fossil site

Karoo Basin, South Africa

One of the most complete records of Permian land animals in the world

Sources: Day & Rubidge 2021 (Frontiers in Earth Science)

Chapter III · Step 8 · 260.6 → 259.1 million years ago

The Emeishan eruptions

A large igneous province (LIP) is a region where enormous volumes of magma erupt in a geologically short time. Emeishan is the smallest LIP in this story, but much of its lava poured into shallow seas, causing steam-driven (phreatomagmatic) explosions that could loft gases high into the atmosphere.

1. Basalt erupts on the South China block near the equator
2. Lava meets shallow sea water: violent steam explosions
3. CO₂ and SO₂ cause warming and brief cooling episodes (debated)
4. Oceans lose oxygen and acidify; carbonate rocks almost vanish at high latitudes

Eruptions began

260.55 Ma

±0.07 Myr (Huang et al. 2022)

85% of volume

~1.45 Myr

±0.50 Myr

Area

≥ 0.3 million km²

What survives today (Shellnutt 2015)

Found today in

Yunnan, Sichuan, Guizhou, northern Vietnam

Mount Emei, a sacred Buddhist mountain, is capped by this basalt

Sources: Wignall et al. 2009 (Science); Huang et al. 2022 (Geology); Bond et al. 2015 (GSA Bulletin); Shellnutt 2015 (Geoscience Canada)

Chapter III · Step 9 · ~259.5 million years ago

A sixth mass extinction, or a regional crisis?

In the tropical seas, giant fusulinids, giant alatoconchid bivalves and reef-building calcareous algae disappeared. On land, only one dinocephalian genus survived. How severe the crisis was overall is still disputed.

Marine genera

~25–47%

Stanley 2016 gives 33–35%

Marine species

~60%

Estimate by Rampino & Shen 2021

Karoo land animals

74–80%

Of genera (Day et al. 2015)

Last dinocephalians

260.26 Ma

Age of an ash bed in the Karoo (Day & Rubidge 2021)

Both sides of the argument

• Major Rampino & Shen (2021) argue it belongs with the Big Five once separated from the end-Permian.
• Unclear Clapham et al. (2009) found a steady decline once sampling bias is corrected; a 2023 review does not count it as a mass extinction.
• Not in step Marine losses in South China mostly predate ~261.6 Ma, land losses in the Karoo came near 260.3 Ma, and eastern Australia shows almost no extinction.

Sea level was at its lowest of the Palaeozoic at this time, so few rocks of this age survive, which makes the severity hard to measure.

Sources: Clapham et al. 2009 (Paleobiology); Rampino & Shen 2021 (Historical Biology); Day & Rubidge 2021; Zhang et al. 2019 (J. Geol. Soc.); Marshall 2023 (Cambridge Prisms: Extinction)

Chapter IV · Step 10 · ~253 million years ago

The world before the Great Dying

By the Late Permian almost all land was joined in Pangaea. The southern hemisphere was covered by Glossopteris forests, later turned into the coal seams of Australia and India. Therapsids were diverse on land, from predatory gorgonopsians to plant-eating dicynodonts, alongside large armoured pareiasaurs.

CO₂ beforehand

~426 ppm

Wu et al. 2021

Tropical sea surface

~23 °C

Before the extinction (Burgess et al. 2014)

Trilobites

One order left

In decline since the Devonian; they disappear for good in this event

Sources: Wu et al. 2021 (Nature Communications); Burgess et al. 2014 (PNAS)

Chapter IV · Step 11 · 252.2 → 251.9 million years ago

The Siberian Traps

One of the largest volcanic episodes in Earth’s history. Lava began flowing around 252.2 million years ago, but the turning point came around 251.9 million years ago, when magma began to spread underground as sheets (sills) through the Tunguska Basin, which was packed with coal, oil shale and rock salt. The heat baked these rocks and released vast amounts of gas.

1. Lava pours from fissures over millions of km²
2. Underground magma bakes coal and salt, blasting out kilometre-wide craters
3. CO₂, methane and ozone-destroying halogen compounds are released
4. Atmospheric CO₂ rises about 6-fold within ~75,000 years

Carbon released

~36,000 Gt C

~5 Gt C per year in the first pulse (Cui et al. 2021)

Atmospheric CO₂

426 → ~2,507 ppm

Wu et al. 2021

Area

2.5–5 million km²

Boscaini et al. 2022; Reichow et al. 2009

Volume

~3 ± 1 million km³

Some estimates reach ~6 million km³

In this scene, the bright flashes stand for the breccia-pipe explosions that formed when magma burned through buried coal. The lava field is drawn at its approximate size on the 250-million-year map.

Sources: Burgess et al. 2017 (Nature Communications); Svensen et al. 2009 (EPSL); Cui et al. 2021 (PNAS); Wu et al. 2021 (Nature Communications)

Chapter IV · Step 12 · 251.94 → 251.88 million years ago

The Great Dying

The largest extinction in Earth’s history. Most of it happened within about 61,000 ± 48,000 years, a geological blink. On land, forests and animals began to collapse 60,000–370,000 years before the oceans did.

1. CO₂ rises; sea surfaces warm about 10 °C (from ~23 to ~33 °C)
2. Warm water holds less oxygen while animals need more; this explains over half of the marine extinction (Penn et al. 2018)
3. The ocean acidifies: surface pH falls about 0.6–0.7 in ~10,000 years
4. Weathering adds nutrients; the seas turn anoxic, with episodes of hydrogen sulphide

Qualitative curves drawn through the starting and peak values in the literature (Wu et al. 2021; Burgess et al. 2014; Sun et al. 2012), not point-by-point data.

Marine species

81–94%

The often-quoted 90–96% is too high (Stanley 2016)

Marine genera

56–83%

Depending on method

Land vertebrates

~70%

Of families (Dal Corso et al. 2022)

Insects

8–9 orders

The only mass extinction of insects

Gone for good

Trilobites Rugose and tabulate corals Blastoids Fusulinids Gorgonopsians Glossopteris forests

Evidence

Meishan in Zhejiang, China, is the global reference section for the Permian–Triassic boundary. Its ash beds date the extinction to within tens of thousands of years.

Sources: Burgess et al. 2014 (PNAS); Penn et al. 2018 (Science); Clarkson et al. 2015 (Science); Jurikova et al. 2020 (Nature Geoscience); Dal Corso et al. 2022 (Nat. Rev. Earth Environ.)

Chapter IV · Step 13 · 251.9 → ~243 million years ago

The survivors

The Early Triassic was a hothouse. Tropical sea surfaces reached about 40 °C and land temperatures perhaps 50–60 °C. Fish and reptiles avoided the tropics, and the surviving ecosystems were dominated by a handful of species.

Lystrosaurus

>90%

Of Early Triassic vertebrates in the Karoo (Botha & Smith 2020)

Tropical sea surface

~40 °C

Sun et al. 2012

Recovery

~8–9 Myr

Some groups such as ammonoids rebounded in 1–3 Myr, but stable complex ecosystems returned only in the Middle Triassic (Chen & Benton 2012)

Survivors and winners

Lystrosaurus Archosauromorphs (ancestors of crocodiles and dinosaurs) Ammonoids Scleractinian corals (Middle Triassic)

Gaps in the rocks

The Early Triassic has almost no coal and no reefs anywhere on Earth. Geologists call these the coal gap and the reef gap.

GFZ researchers estimate that today’s yearly human CO₂ emissions are about 14 times the yearly rate during the Great Dying, although the total released so far is far smaller.

Sources: Botha & Smith 2020 (PeerJ); Sun et al. 2012 (Science); Chen & Benton 2012 (Nature Geoscience); GFZ 2020 (Jurikova et al.)

Chapter V · Step 14 · ~202 million years ago

The Late Triassic world

Pangaea was still whole, but rift valleys were opening along the line that would later split into the Atlantic. On land, crurotarsans (crocodile-line archosaurs) were the main predators and plant-eaters. In the sea lived the last conodonts and the ceratitid ammonoids.

Land predators

Rauisuchians

Such as Postosuchus, an upright-walking crocodile relative

Riverbanks

Phytosaurs

Croc-like, but with nostrils near the eyes

Dinosaurs

Already diverse

Small theropods like Coelophysis and sauropodomorphs, but not yet dominant

Sources: Olsen et al. 2022 (Science Advances); Blackburn et al. 2013 (Science)

Chapter V · Step 15 · 201.6 → 201.0 million years ago

The Central Atlantic Magmatic Province (CAMP)

The largest known igneous province by area. Magma intruded sedimentary rocks around 100,000 years before lava reached the surface. The extinction happened about 13,000 years before the first lava flow in New Jersey’s Newark Basin; in Morocco, the extinction level sits within the first lava flow.

1. Magma intrudes sediments and salt beds in the Amazon Basin
2. Lava erupts in four pulses over ~600,000 years; CO₂ roughly doubles with each
3. SO₂ causes brief winters, cooling up to ~10 °C, against long-term warming of ~3–4 °C
4. The ocean acidifies, pH falling at least 0.29; shell builders are hit hard

Extinction age

201.564 Ma

±0.015 Myr (Blackburn et al. 2013)

Area

>10 million km²

Volume 2–3 million km³ or more

CO₂, first pulse

~2,000 → ~4,400 ppm

From fossil soils; leaf-pore methods give much lower values

Ocean pH

down ≥0.29

Trudgill et al. 2025

The basalts of New Jersey and Morocco once lay side by side, before Pangaea split and the Atlantic opened between them.

Sources: Blackburn et al. 2013 (Science); Davies et al. 2017 (Nature Communications); Schaller et al. 2011 (Science); Capriolo et al. 2020 (Nature Communications); Trudgill et al. 2025 (Nature Communications)

Chapter V · Step 16 · 201.4 million years ago → Jurassic

The way opens for the dinosaurs

After the CAMP eruptions most crocodile-line archosaurs were gone, leaving dinosaurs to take over land ecosystems in the Jurassic. Marine ecosystems recovered in about 1–2 million years, far faster than after the Great Dying.

Species lost

~70–80%

Stanley 2016 declined to estimate because the data are disputed

Genera lost

~37–73%

A wide range depending on method

Ice in a greenhouse world

Ice-rafted pebbles, Junggar Basin, China

High-latitude lakes froze during volcanic winters (Olsen et al. 2022)

Gone

The last conodonts Phytosaurs Aetosaurs Rauisuchians Giant temnospondyls Almost all ceratitid ammonoids

Survivors

Dinosaurs Pterosaurs Crocodylomorphs Mammal ancestors

The global reference section for the Triassic–Jurassic boundary is at Kuhjoch in the Karwendel Mountains of Austria.

Next · 66 million years ago The last day of the dinosaursThe 3D model of the Chicxulub impact Sources: Olsen et al. 2022 (Science Advances); Hesselbo et al. 2002 (Geology); Hillebrandt et al. 2013 (Episodes)

Epilogue · comparing the five

What the five have in common

None had a single cause, but every one involved rapid climate change and oxygen-starved oceans, and several involved acidified seas. Four of the five coincided with eruptions of a large igneous province; the earliest is tied to an ice age instead.

Event	Age (Ma)	Marine species lost	Main cause
I End-Ordovician	~445–443	~85%	Ice age and sea-level fall, then anoxic seas
II Late Devonian	371.9 · 359.0	~40–75%	Anoxic seas, cooling pulses, nutrients from forests, Viluy volcanism
III End-Guadalupian *	~260–259.5	~60%	Emeishan volcanism, anoxic and acidified seas
IV End-Permian	251.9	81–94%	Siberian Traps; CO₂ up ~6×, warming ~10 °C
V End-Triassic	201.6	~70–80%	CAMP; CO₂ in pulses, volcanic winters, acid seas
End-Cretaceous	66.0	~76%	Chicxulub asteroid (and Deccan volcanism)

* Whether the end-Guadalupian counts as a mass extinction is still debated. All species figures are estimates extrapolated from genus and family data.

Reading the numbers

• Ranges Different research groups use different methods, so the ranges are wide, especially for the Late Devonian and the Triassic.
• Speed The Great Dying unfolded in about 60,000 years. GFZ researchers estimate today’s yearly human CO₂ emissions at about 14 times the yearly rate back then.
• Maps Continental positions come from the PALEOMAP reconstruction; the older the map, the larger the uncertainty.

The next one · 66 million years ago The last day of the dinosaursContinue with the 3D model of the Chicxulub impact

Key sources

Stanley 2016, PNAS: magnitudes of the major marine mass extinctions Marshall 2023: the status of the Big Five, forty years on Finnegan et al. 2011, Science: the Late Ordovician glaciation Da Silva et al. 2020: age and pacing of the Kellwasser events University of Cambridge: the end-Devonian ozone hypothesis Day & Rubidge 2021: the end-Guadalupian extinction on land Burgess et al. 2014, PNAS: timeline of the end-Permian extinction MIT News: underground magma and the Great Dying GFZ: ocean acidification during the Great Dying (Jurikova et al. 2020) Davies et al. 2017: CAMP magma and the end-Triassic extinction Eos: volcanic winters and the dinosaurs (Olsen et al. 2022) EarthByte: Scotese & Wright (2018) PaleoDEMs, CC BY 4.0

The ancient globes are built from the Scotese & Wright (2018) PaleoDEMs, and evidence sites are rotated to their ancient positions with the PALEOMAP plate model. Land colours are an artistic interpretation. The modern globe uses NASA Blue Marble imagery. All full-screen stills are AI-generated to aid the imagination; details of animals and plants may not match the fossil evidence exactly.