Toarcian

The Toarcian is an important time in Earth's history. It is part of the Early or Lower Jurassic. It lasted from about 184.2 million years ago to 174.7 million years ago. This time comes after the Pliensbachian and before the Aalenian in the geologic timescale.

The Toarcian began with a big change called the Toarcian Oceanic Anoxic Event. During this time, the oceans had less oxygen. This caused many sea creatures to die out and the Earth to get warmer. Because of these changes, the fossils from this time look different from those before it.

At the end of the Toarcian, scientists think there was a cooling period known as the Comptum Cooling Event. However, there is some debate about whether this cooling happened all around the world or just in some places.

Stratigraphic definitions

The Toarcian is an old time period named after the city of Thouars in France. A scientist described it in 1842 after studying rocks near the city.

During this time, special fossils called ammonites appeared. Scientists use these fossils to know when the Toarcian started and ended. In Europe, these rocks are part of a group called the Lias. Far away, in a place called the Tethys domain, many types of ammonites lived during this time.