Triassic–Jurassic extinction

The Triassic–Jurassic (Tr-J) extinction event, often called the Triassic–Jurassic mass extinction (TJME) or end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, 201.4 million years ago. It was one of five major extinction events during the Phanerozoic, and it changed life on Earth forever.

In the oceans, many types of sea creatures died out. Groups like corals, bivalves, brachiopods, bryozoans, and radiolarians lost many of their species, and conodonts disappeared completely. On land, most large reptiles called archosauromorphs went extinct, except for crocodylomorphs, dinosaurs, and pterosaurs. These survivors became the main land animals for the next 135 million years. Plants also changed greatly during this time.

Scientists believe the main cause of this extinction was huge volcanic eruptions in the Central Atlantic magmatic province (CAMP). These eruptions poured lots of carbon dioxide into the air, leading to strong global warming and ocean acidification. They also released toxic mercury. Some older ideas suggest climate changes, sea level shifts, or asteroid impacts might have played a role, but the volcanoes are thought to be the main reason.

Research history

Early studies of the Triassic-Jurassic extinction often focused on slow changes in the environment. A scientist named Edwin H. Colbert thought that changes in rain and sea levels slowly reduced land, leading to the extinction.

Later, in the 1980s, Jack Sepkoski identified this event as one of the five big mass extinctions in Earth's history. Some scientists thought an asteroid impact caused it, like the one that ended the dinosaurs. But today, most experts believe huge volcanic eruptions in the Central Atlantic magmatic province were the main cause. This idea grew after similar volcanic activity was linked to another ancient extinction, the Permian-Triassic extinction event.

Effects

The Triassic-Jurassic extinction was a big change that happened about 201.4 million years ago. It changed life in the oceans and on land.

In the seas, many kinds of sea life disappeared. Corals, bivalves, brachiopods, and bryozoans lost a lot of their variety, and conodonts vanished completely. But fish and some shellfish were less affected.

On land, the extinction changed animals and plants. Many amphibians and reptiles that were common before did not survive. Dinosaurs began to thrive and fill the empty places. Plants also changed, with some disappearing while others, like certain ferns, became more common. This event helped shape the animals and plants that would live on Earth for millions of years after.

Possible causes

The main idea for the Triassic–Jurassic extinction is huge volcanic eruptions from the Central Atlantic Magmatic Province (CAMP). These eruptions were some of the biggest ever known on Earth. They spread across parts of Europe, Africa, South America, and North America. Evidence shows these eruptions happened close to when the extinction took place. Changes in carbon in old soils and ocean sediments connect the two.

These volcanoes put out lots of carbon dioxide, a gas that traps heat. Before the extinction, carbon dioxide levels were about 1,000 parts per million. During the extinction, they rose to 1,300 parts per million and went up more. This quick warming changed the climate and made life hard for many species. The warmth also caused problems like more wildfires and less oxygen in the oceans, which helped cause the extinction.

Comparisons to present climate change

Scientists have found that a lot of carbon was released during a time of strong volcanic activity called the CAMP volcanism. This happened about 201.4 million years ago and caused big changes in the Earth's climate. Many sea creatures were lost because of this.

Today, people are putting carbon dioxide into the air very fast, like what happened back then. This is making the Earth warmer quickly. Some scientists worry this could harm ocean animals, like coral reefs. They think it is important to reduce carbon emissions to help protect our planet.