Triassic–Jurassic extinction

A long time ago, the world changed.

Many living things died out. This happened when huge volcanoes erupted.

These volcanoes sent much gas into the air. This made the world very hot. It also changed the ocean water.

Many sea animals disappeared. Corals and shells had a hard time.

On land, many reptiles died out. But some animals stayed safe. Dinosaurs and mammals lived through it. These animals became the main leaders of the land. It was a big change for our world.

A long time ago, the world went through a big change. This was a mass extinction. That means many types of living things died out.

This event happened at the end of the Triassic period. It marks the start of the Jurassic period.

Scientists think huge volcanoes caused this. These volcanoes were in a place called the Central Atlantic Magmatic Province. We call this CAMP for short.

These eruptions let out much carbon dioxide. This gas made the Earth very hot. It also made the ocean water acidic. Acidic water is water that has changed in a way that can harm life.

Many sea animals were lost. About 23% to 34% of marine groups died out. Corals were hit very hard.

Many small creatures called conodonts died out completely. On land, many reptiles also disappeared. But some animals stayed safe. Dinosaurs, mammals, and pterosaurs survived.

Because they lived, they became the main animals on land for a long time.

A mass extinction is a time when many different types of living things die out. One of the most important events like this happened at the end of the Triassic period. This event marks the boundary where the Triassic ends and the Jurassic begins. It is one of the five major extinction events in Earth's history. This change profoundly affected life both on land and in the deep oceans.

Scientists believe this happened because of huge volcanic eruptions. These eruptions occurred in the Central Atlantic magmatic province, or CAMP. This area released massive amounts of carbon dioxide into the air. The gas caused the Earth to undergo global warming. It also led to ocean acidification, which means the water became more acidic. The volcanoes also released large amounts of toxic mercury into the environment.

Researchers have spent many years studying this event. In the mid-20th century, most scientists thought environmental changes were very gradual. A paleontologist named Edwin H. Colbert suggested that changes in rainfall and sea levels were the cause. Later, in the 1980s, Jack Sepkoski identified this as one of the "Big 5" mass extinctions. For a while, some people thought an asteroid strike might be the cause. However, the volcanic theory from the 1990s is now the main scientific consensus.

Many living things were lost during this time. In the ocean, about 23% to 34% of marine genera disappeared. Corals were hit very hard, with about 96% of coral genera dying out. Small creatures called conodonts were completely wiped out.

On land, many reptiles became extinct. However, dinosaurs, pterosaurs, and mammals were left largely untouched. This allowed those groups to become the dominant animals for the next 135 million years.

This event changed how life works in the sea and on land. It helped finish the shift from old types of sea life to the modern types we see today. Even though many things died, some life recovered quite quickly. In some places, sea life began to return almost immediately after the extinction. Large bivalves, which are shell-bearing animals, began to reappear soon after. This shows how life can find new ways to thrive after a hard time.

The Triassic–Jurassic extinction event, often called the TJME, marks the boundary between the Triassic and Jurassic periods. This event is recognized as one of the five major mass extinction events during the Phanerozoic eon. It was a period of profound biological change that affected life across the entire planet. The crisis fundamentally reshaped ecosystems in both the deep oceans and on land.

By removing many established species, the event cleared the way for new groups to dominate the Earth for millions of years.

Scientists generally agree that massive volcanic activity caused this extinction. This activity took place in the Central Atlantic magmatic province, known as CAMP. This was a large igneous province where immense amounts of lava were released. The eruptions discharged vast quantities of carbon dioxide into the Earth's atmosphere. This gas caused significant global warming and led to ocean acidification, which is the lowering of the ocean's pH. Additionally, the volcanoes released immense amounts of toxic mercury into the environment. This combination of heat, acid, and toxins created a lethal world for many species.

The marine environment experienced a massive loss of biodiversity. Between 23% and 34.1% of all marine genera disappeared during this time. Corals were devastated, with approximately 96% of coral genera dying out. This led to a "coral gap" in the Tethys Ocean where reefs almost entirely vanished. Other groups like bivalves and brachiopods also suffered heavy losses. Specifically, conodonts, which were important vertebrate groups, were completely wiped out.

However, some groups like gastropods and certain fish were relatively unaffected by the crisis.

Life on land was also heavily impacted, though the patterns were different. It is estimated that 42% of all terrestrial tetrapods, or four-limbed vertebrates, went extinct. Many large amphibians, such as the Temnospondyli, saw a major decline in diversity. Specifically, groups like the capitosaurs and plagiosaurids were among the major victims.

Many archosauromorph reptiles also vanished. However, certain groups like dinosaurs, pterosaurs, and mammals were left largely untouched. This survival allowed these animals to become the dominant land creatures for the next 135 million years.

Our understanding of this event has changed as scientific methods improved. In the mid-20th century, most researchers followed the paradigm of uniformitarianism. This meant they believed Earth's history was shaped by gradual changes rather than sudden catastrophes. Paleontologist Edwin H. Colbert suggested that changes in rainfall and sea levels caused the extinction. In the 1980s, Jack Sepkoski identified the TJME as one of the "Big 5" mass extinctions. During the 1980s and 1990s, some scientists even proposed an asteroid impact as the cause.

Today, the volcanic theory involving CAMP is the scientific consensus.

Following the extinction, different types of marine life began to recover at different speeds. In some regions, such as the British Early Jurassic environments, benthic ecosystems recovered very rapidly. In the Neuquén Basin, large bivalves began to reappear shortly after the event.

In other areas, like the northern Tethys, recovery was much slower. In those places, microbial carbonate producers dominated the seafloor for a long time. The influx of silica from weathered volcanic rocks also allowed siliceous sponges to dominate the immediate aftermath.

The Triassic–Jurassic extinction was a pivotal moment in the history of life. It completed the transition from the Paleozoic evolutionary fauna to the Modern evolutionary fauna. This shift determined which types of organisms would rule the oceans in the modern era. On land, the extinction facilitated a massive biological turnover. It moved the world from an era of diverse ancient reptiles and amphibians into the age of dinosaurs. This event shows how sudden geological changes can completely rewrite the story of life on Earth.