A conifer-dominated Early Triassic flora from Southwest China

Paleozoic and Mesozoic SeasEarth’s oceans were full of life during the Paleozoic and Mesozoic eras. In the Paleozoic Era, 541 to 252 million years ago, the seas were home to trilobites, brachiopods, and early fish. Coral reefs began to form, and the first vertebrates with jaws appeared. The Mesozoic Era, 252 to 66 million years ago, is often called the Age of Reptiles, but the oceans were just as important. Large marine reptiles like plesiosaurs and mosasaurs ruled the seas, along with...

Paleozoic Plate TectonicsThe Paleozoic Era lasted from about 541 to 252 million years ago. During this time, Earth's surface changed dramatically. The movement of tectonic plates, large pieces of Earth's crust, caused continents to shift, oceans to open and close, and mountains to rise. These slow but powerful movements shaped the land and affected life. By the end of the Paleozoic, most of Earth's land had joined into one supercontinent, Pangaea.Science and Engineering Practice (SEP):...

The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.

Precambrian ContinentsThe Precambrian period is the longest chapter in Earth’s history, covering almost 88% of the planet’s past. It started about 4.6 billion years ago, when Earth first formed, and lasted until around 541 million years ago. Back then, the world looked very different. There were no plants, no animals, and no oceans like we see today. The first continents started taking shape as molten rock cooled and hardened. These landmasses were small, unstable, and constantly changing...

Seedless Vascular Plants Were the First Tall Plants on Earth

Mesozoic Plate TectonicsImagine Earth’s land as one giant puzzle piece. A long time ago, during the Mesozoic Era, all the land on Earth was connected to one big supercontinent called Pangaea. Over millions of years, the pieces of this giant puzzle slowly drifted apart, forming the continents we see today. This movement happened because of plate tectonics, the slow shifting of vast sections of Earth’s crust. As these plates moved, they caused earthquakes, created mountains, and even changed...