Manash (Subhaditya Edusoft): The Devonian extinction (372

The Devonian extinction (372–359 million years ago) was a prolonged crisis that wiped out about 75% of marine species, collapsing reef ecosystems and ending the dominance of armored placoderms, while land animals like early tetrapods and arthropods were less severely affected. It was not a single event but a series of extinction pulses, most notably the Kellwasser and Hangenberg events.

🌍 Overview of the Devonian Extinction

Timeframe: Late Devonian, ~372–359 million years ago.

Nature: A drawn-out series of extinction pulses rather than one catastrophic event.

Severity: Eliminated ~75% of species, ~20% of animal families.

Major Events:

Kellwasser crises (~372 Ma): Severe marine die-offs.

Hangenberg event (~359 Ma): Final pulse at the Devonian–Carboniferous boundary.

MARINE ANIMALS LIKE DUNKLEOSTEUS,TRILOBITES,CORALS SOME SHARKS, LUNGFISH, DEVONIAN SCORPIONS,AMMONITES, BECOME EXTINCT

🌊 Marine Animals Affected

Reef Builders: Stromatoporoid sponges and corals collapsed, ending the largest reef systems in Earth’s history.

Trilobites & Brachiopods: Many lineages perished, reducing Paleozoic diversity.

Placoderms (Armored Fish): Apex predators like Dunkleosteus vanished.

Jawed Vertebrates: Suffered a bottleneck, reshaping fish evolution.

Cephalopods (Ammonoids): Experienced heavy losses but some survived.

🌱 Land Animals & Plants

Terrestrial Plants: The rise of deep-rooted forests accelerated weathering and nutrient runoff, indirectly triggering marine anoxia.

Arthropods: Insects and arachnids were relatively unaffected compared to marine life.

Early Tetrapods: Survived but faced ecological stress; the extinction shaped their evolutionary trajectory.

⚠️ Causes

Ocean Anoxia: Widespread oxygen depletion in seas.

Climate Change: Shifts from greenhouse to icehouse conditions.

Volcanism: Possible eruptions from the Viluy Traps.

Nutrient Runoff: Forest expansion caused eutrophication in shallow seas.

Asteroid Impacts: Suggested but less certain.

📊 Comparison Table

Group/Feature Role in Ecosystem Fate in Devonian Extinction

Stromatoporoids & Corals Reef builders Collapsed, reefs destroyed

Trilobites Marine arthropods Many lineages extinct

Placoderms (e.g., Dunkleosteus) Apex predators Extinct

Ammonoids Marine cephalopods Heavy losses, few survived

Brachiopods Marine filter feeders Major decline

Forests (Archaeopteris) Terrestrial plants Expanded, triggered runoff

Arthropods (insects, arachnids) Land colonizers Largely unaffected

Early Tetrapods Proto-amphibians Survived, stressed

🔑 Key Takeaways

The Devonian extinction was primarily a marine crisis, devastating reefs and fish diversity.

Land ecosystems were less affected, though forests indirectly contributed to marine collapse.

It reshaped evolution, paving the way for Carboniferous amphibians and new fish lineages.

the causes of the Devonian extinction The above picture highlights the interplay of volcanism, ocean anoxia, climate shifts, and nutrient runoff from expanding forests, all converging into the mass die-off between 372–359 million years ago.

You can use this image as a clear diagrammatic reference to understand how each factor contributed to the collapse of ecosystems.

Would you like me to also create a scene-style visualization — for example, showing a Devonian reef collapsing with Dunkleosteus and trilobites dying in oxygen-poor waters — to give it a more cinematic paleoart feel?

The above visually combines two perspectives:

🕰️ Timeline: showing the Early, Middle, and Late Devonian periods, highlighting the Kellwasser (~372 Ma) and Hangenberg (~359 Ma) events that marked the major extinction pulses.

🌍 Landmass Map: depicting Laurussia in the north and Gondwana in the south, separated by the Proto-Tethys and Panthalassa Oceans, with shallow seas, mountain belts, and early ice sheets forming in Gondwana.

This image captures how continental positions and climatic shifts intertwined with the extinction timeline — a perfect reference for understanding the global scope of the Devonian crisis.

Animals that went extinct during the Devonian period — a haunting underwater tableau of collapse.

At its center lies the massive Dunkleosteus, the armored apex predator of Devonian seas, now lifeless on the ocean floor. Around it, trilobites, goniatites, crinoids, horn corals, and brachiopods lie scattered among decaying reefs, symbolizing the devastation of marine biodiversity.

The dim green light and drifting debris evoke the oxygen-depleted “dead zones” that marked the end of the Devonian’s vibrant ecosystems.

TIKTALIK EXTINCTION DUE TO VOLCANIC ERUPTION DURING DEVONIAN PERIOD

🦎 What Tiktaalik Was

Tiktaalik was a lobe-finned fish that bridged the evolutionary gap between aquatic fish and early land vertebrates. It had:

Fins with wrist-like bones, capable of supporting its body in shallow water or mudflats.

Flat head and eyes on top, adapted for peering above water.

Lungs and gills, allowing it to breathe both air and water.

It lived in river deltas and coastal wetlands of what is now Arctic Canada (then part of the supercontinent Laurussia).

TIKTALIK EXTINCTION DUE TO VOLCANIC ERUPTION DURING DEVONIAN PERIOD

🌍 What Happened During the Devonian Extinction

The Late Devonian extinction (especially the Kellwasser and Hangenberg events) devastated marine ecosystems:

Oxygen depletion (anoxia) in shallow seas.

Climate cooling and glaciation.

Collapse of reef and fish diversity.

Tiktaalik’s habitat—shallow freshwater and coastal zones—was affected, but it likely disappeared before the final Hangenberg event (~359 Ma). Fossil evidence suggests Tiktaalik’s lineage did not survive into the Carboniferous, but its descendants (early tetrapods) did.