Mesozoic

The Mesozoic Era is a time in Earth's geological history. It lasted from about 252 to 66 million years ago. It has three main parts called the Triassic, Jurassic, and Cretaceous Periods. This era is known for the dinosaurs and many other amazing animals.

During the Mesozoic, Earth looked very different. The weather was warm and wet. The big land Pangaea began to break apart into the continents we have today. This time is often called the Age of the Dinosaurs because big reptiles were the main land animals. They lived after a big event called the Permian–Triassic extinction event, and they ended when another big event happened, the Cretaceous–Paleogene extinction event.

Many new kinds of life appeared in the Mesozoic. The first mammals appeared, but they were very small. The first flowering plants started to grow, which later changed the world’s forests. Birds came from some kinds of dinosaurs, beginning with early birds and later true toothless birds. The Mesozoic was a time of big changes and excitement in Earth’s history.

Naming

The phrase "Age of Reptiles" was used by a scientist named Gideon Mantell. He thought this time was mostly ruled by reptiles like Iguanodon, Megalosaurus, Plesiosaurus, and Pterodactylus.

The name "Mesozoic" was suggested in 1840 by a geologist named John Phillips. It means 'middle life'. It comes from Greek words for 'between' and 'animal, living being'. The Mesozoic is the middle time between the Paleozoic ('old life') and the Tertiary. It is also close to the Cenozoic ('new life') and the Proterozoic ('earlier life') times.

Geologic periods

The Mesozoic Era came after the Paleozoic. It lasted about 186 million years, from 251.902 to 66 million years ago. Then the Cenozoic Era began.

The Mesozoic is divided into three parts, called periods: the Triassic Period, the Jurassic Period, and the Cretaceous Period.

The Mesozoic started after the Permian–Triassic extinction event, when many plants and animals died out. It ended with the Cretaceous–Paleogene extinction event. A big space rock may have hit Earth, which led to the end of the dinosaurs, except for birds. Birds are considered modern dinosaurs.

Paleogeography and tectonics

The Mesozoic Era had gentle movements of Earth's plates. One big event happened in the Arctic, forming mountain ranges like the Innuitian orogeny and the Brooks Range.

During this time, a huge landmass called Pangaea began to break apart. It split into two smaller continents: Laurasia in the north and Gondwana in the south. This splitting created the edges of continents we see today, like along the Atlantic coast. By the end of the Mesozoic, these continents had moved closer to their current shapes. Laurasia became North America and Eurasia, while Gondwana divided into South America, Africa, Australia, Antarctica, and the Indian subcontinent.

Climate

The Triassic period was dry and changed a lot, especially in the middle of a big land called Pangaea. Far from the coasts, temperatures changed a lot, and large deserts may have existed. There were also times with more rain, like during the Carnian Pluvial Event.

During the Jurassic, sea levels rose because new ocean floor was forming. This flooded coastal lands. As Pangaea broke apart, it made more shorelines. The weather became more humid and temperatures rose.

The Cretaceous climate is not very clear, but many think there was a lot of carbon dioxide in the air. This made temperatures about the same everywhere and a little warmer than today.

Life

The Mesozoic Era brought many changes to plant and animal life on Earth. On land, gymnosperms such as conifers and cycads were the most common plants. One special plant from this time is the Ginkgo, which still grows today as Ginkgo biloba. Later, flowering plants began to appear and spread from the tropics toward the poles.

Many new animals appeared after a big event at the end of the Permian Period caused many species to disappear. Dinosaurs, pterosaurs, and reptiles like ichthyosaurs and plesiosaurs became common. The Jurassic Period was a time when these animals grew in variety, and it was also when the first birds and advanced mammals appeared. Insects also evolved and became more diverse. In the oceans, tiny plants called plankton changed from mostly green types to others with red-algal-derived parts, perhaps because some metals became less common in the water.