PALEOZOIC ERA · LATE DEVONIAN

DEVONIAN EXTINCTION

When ancient life nearly ended — and a new world began

~375 – 359 MILLION YEARS AGO

When Did It Happen?

Placing the event in deep time

Cambrian

541 – 485 Ma

Ordovician

485 – 443 Ma

Silurian

443 – 419 Ma

DEVONIAN
419 – 359 Ma

Carboniferous

359 – 299 Ma

── TIME FLOWS RIGHT ──▶

359 Ma

End of the Devonian Period

375 Ma

Kellwasser Events Begin

~16 Ma

Duration of Crisis Phase

How Long Did It Take?

A prolonged collapse — not a single catastrophe

~20

MILLION

YEARS

of extinction pressure across multiple pulses

Kellwasser Events

~375 – 374 Ma

Two massive anoxic ocean episodes, each triggering rapid extinction pulses across marine ecosystems

Intercalation Phase

~374 – 362 Ma

Repeated pulses of environmental stress and extinction pressure over millions of years

Hangenberg Event

~359 Ma

The final catastrophic collapse — a global crisis that ended the Devonian Period

What Caused the Extinction?

A perfect storm of environmental catastrophes

🌿 Land Plant Explosion

Vascular plants colonized land, drastically altering CO₂ levels and flooding oceans with nutrients, triggering widespread dead zones.

🌊 Ocean Anoxia

Nutrient blooms triggered massive oxygen-depleted dead zones at depth. Marine life suffocated on a global scale.

❄️ Global Cooling

CO₂ drawdown by land plants caused rapid cooling and possible polar glaciation, stressing tropical marine ecosystems.

🌋 Volcanic Activity

Siberian and Viluy trap eruptions may have destabilized climate through CO₂ and SO₂ spikes over long timescales.

☄️ Bolide Impacts?

Evidence of possible multiple extraterrestrial impacts exists, though their role as a primary driver remains scientifically contested.

🌐 Sea Level Changes

Repeated transgression and regression cycles wiped out the shallow marine reef ecosystems that dominated Devonian seas.

Life Before the Extinction

A world dominated by the sea — and a changing land

THE DEVONIAN OCEAN

Reef systems dominated by stromatoporoids and tabulate corals — rivaling today's Great Barrier Reef

Armored fish (placoderms) ruled as apex predators — Dunkleosteus reaching 9 meters

Trilobites still widespread across the ocean floor

Brachiopods and ammonoids thriving in vast numbers

Crinoids carpeting sea floors; first sharks appearing

🌿 The Land Revolution

First forests emerged (Archaeopteris trees up to 10m). Tetrapods beginning to crawl onto land. Early insects, arachnids, and vascular plants spreading globally.

🪸 The Age of Fishes

The Devonian earned its nickname from jaw-dropping fish diversity. But it was also Earth's first golden age of coral reefs — ecosystems that would almost entirely vanish.

What Went Extinct?

The casualties of the Late Devonian crisis

Stromatoporoid Reefs

Primary reef-builders nearly wiped out

~90%extinct

Trilobites

Many major families eliminated forever

~70%extinct

Placoderms

All armored fish — completely gone

100%extinct

Brachiopods

Massive loss across many families

~70%extinct

Ammonoids

Nearly all lineages lost

~70%extinct

Rugose Corals

Major reef architects wiped out

~80%extinct

Scale of the Extinction

One of the "Big Five" mass extinctions in Earth's history

75%

of all species
on Earth vanished

~19–20% of all families
~50% of all genera

BIG FIVE EXTINCTIONS — % SPECIES LOST

Ordovician 443 Ma

86%

Devonian 359 Ma ★

75%

Permian 252 Ma

96%

Triassic 201 Ma

80%

Cretaceous 66 Ma

76%

Macroevolutionary Aftermath

New winners emerged from the chaos

BEFORE

Placoderms dominated the seas

→

AFTER

Ray-finned fish radiated explosively into all vacated niches

BEFORE

Lobe-finned fish lived in shallow water

→

AFTER

Tetrapods conquered land — ancestors of ALL land vertebrates, including us

BEFORE

Stromatoporoid reef builders collapsed

→

AFTER

New reef ecosystems rebuilt with scleractinian corals in the Mesozoic

BEFORE

Sparse plant life on land

→

AFTER

Dense Carboniferous coal forests — a massive global carbon sink, oxygen spiked to 35%

Life After: The Carboniferous World

A transformed biosphere enters a new era

🌲 Carboniferous Forests

Vast coal swamps of lycopsid trees towered 30m tall. Atmospheric oxygen rose to ~35% — enabling giant insects and arthropods unlike anything alive today.

🦎 Tetrapod Radiation

Amphibians diversified widely. By the Carboniferous, amniotes evolved — the first vertebrates fully free of water. The ancestors of reptiles, birds, and mammals.

🦈 Shark Dominance

Sharks survived and radiated spectacularly, filling every niche left empty by the extinct placoderms. The Carboniferous became a golden age for sharks.

🪸 New Reef Builders

Bryozoans and crinoids temporarily filled reef roles. Scleractinian corals would not become dominant until the Triassic — tens of millions of years later.

The
Devonian
Extinction

WHEN~375–359 Million Years Ago

DURATION~20 million years across multiple pulses

CAUSEOcean anoxia, land plants, cooling, volcanism

SCALE~75% of all species on Earth vanished

SURVIVORSSharks, lobe-finned fish, early tetrapods

LEGACYSet the stage for the Carboniferous and the Age of Reptiles

"Extinction is the rule.
Survival is the exception."

— Carl Sagan