what is the history of Earth?(2)

4. Phanerozoic Eon (541 million years ago – Present)

This eon is divided into three major eras, each marked by significant evolutionary and geological changes.

• a. Paleozoic Era (541 – 252 million years ago)
  • Cambrian Explosion: A sudden diversification of life forms occurred around 541 million years ago, with many animal phyla emerging in the oceans, including the ancestors of modern arthropods, mollusks, and vertebrates.
  • First Land Plants and Animals: Around 470 million years ago, plants began colonizing land, followed by the first land animals, such as insects and amphibians.
  • Mass Extinctions: The end of the Paleozoic era was marked by the Permian-Triassic extinction event, the largest mass extinction in Earth’s history, which wiped out about 90% of marine species and 70% of terrestrial species.

• b. Mesozoic Era (252 – 66 million years ago)
  • Age of Dinosaurs: This era saw the rise and dominance of dinosaurs, along with the first birds and mammals.
  • Breakup of Pangaea: The supercontinent Pangaea began to break apart, shaping the continents as we know them today.
  • Cretaceous-Paleogene Extinction: This era ended with another mass extinction event, possibly caused by an asteroid impact, which led to the extinction of the non-avian dinosaurs and paved the way for mammals to dominate.

• c. Cenozoic Era (66 million years ago – Present)
  • Age of Mammals: With dinosaurs gone, mammals rapidly diversified and spread across the planet, leading to the rise of primates, including early human ancestors.
  • Evolution of Humans: The genus Homo emerged about 2.5 million years ago, with modern humans (Homo sapiens) appearing around 300,000 years ago.
  • Recent Ice Ages: Over the past 2.5 million years, Earth has experienced repeated ice ages, with the most recent glaciation ending around 12,000 years ago, coinciding with the rise of human civilization.

5. Anthropocene (debated: Present)

Some scientists argue that we are living in a new epoch called the Anthropocene, marked by the significant impact of human activity on Earth’s geology and ecosystems, particularly since the Industrial Revolution.

Throughout its history, Earth has undergone vast changes, from its fiery origins to the evolution of complex life forms, and continues to evolve with time.