HISTORY OF LIFE ON EARTH AND GEOLOGIC TIME SCALE

• The Earth formed around 4.6 billion years ago
• Life started to appear around 3.5 billion years ago in the form of simple single-celled organisms
• Life evolved and diversified into more complex forms, leading to the incredible biodiversity we see today
• Major Eras in Earth's History


  • Paleozoic Era
  • Mesozoic Era
  • Cenozoic Era
• Major Periods in the Paleozoic Era

  • Cambrian Period
  • Ordovician Period
  • Silurian Period
  • Devonian Period
  • Carboniferous Period
  • Permian Period
• Major Periods in the Mesozoic Era


  • Triassic Period
  • Jurassic Period
  • Cretaceous Period
• The Paleozoic Era saw the emergence and diversification of many new life forms, marking a crucial period in the history of life on our planet
• Cambrian Explosion


  Significant event in life diversification, introducing complex marine animals like trilobites and brachiopods
• Ordovician Period


  Growth of marine life forms, including diverse invertebrates like corals, crinoids, and early fish
• Silurian Period


  Non-vascular plants like mosses and liverworts colonized land, leading to the development of terrestrial ecosystems
• Devonian Period


  Diversification of fish species, development of forests dominated by early vascular plants, emergence of the first tetrapods
• Carboniferous Period


  Lush swamp forests, coal deposits, giant insects, early amphibians
• Permian Period


  Reptile diversification, early mammal-like emergence, largest mass extinction event on Earth's history
• The Paleozoic Era laid the groundwork for the evolution of life on Earth, marking significant milestones in the history of biodiversity and ecosystem development
• The Mesozoic Era spanned approximately 180 million years and is often referred to as the "Age of Reptiles"
• Triassic Period


  Start of the Mesozoic Era, supercontinent Pangaea breaking apart, introduction of early dinosaurs and small mammals
• Jurassic Period


  Dominated by dinosaurs
• Triassic Period


  • The Triassic marked the start of the Mesozoic Era
  • Introduction of early dinosaurs like Eoraptor and Herrerasaurus
  • Introduction of small mammals
• Jurassic Period


  • Dominated by dinosaurs
  • Evolution of various plant and animal species
  • Iconic dinosaurs like Stegosaurus, Brachiosaurus, and Allosaurus
  • Flying reptiles like Pterosaurs
• Cretaceous Period


  • Peak of dinosaur diversity
  • Mass extinction event
  • Dinosaurs like Tyrannosaurus rex, Triceratops, and Velociraptor lived
  • Flying birds evolved from feathered dinosaurs
• The Mesozoic Era is a fascinating time in Earth's history, showcasing the evolution of life and the remarkable diversity of prehistoric creatures that once populated our planet
• Cenozoic Era


  • Current geological era
  • Spanning from approximately 66 million years ago to the present day
  • Often referred to as the "Age of Mammals"
  • Characterized by the evolution and diversification of mammals
  • Rise of humans
• Paleogene Period


  • Recovery and diversification of life after the Mesozoic Era mass extinction
  • Mammals like adapids, omomyids, brontotheres, and early horses thrived and diversified
• Neogene Period


  • Cooler and varied climate
  • Expansion of grasslands
  • First hominids emerged
  • Iconic mammals like saber-toothed cats and mammoths
• Quaternary Period


  • Marked by the Pleistocene epoch
  • Characterized by ice ages
  • Emergence of Homo sapiens
  • Species emerged around 300,000 years ago from megafauna
• The Cenozoic Era is crucial for understanding the development of life on Earth, especially the evolution of mammals and the emergence of humans as the dominant species