Origin and History of Life on Earth PDF

ORIGIN AND HISTORY OF LIFE ON EARTH Brief History of Life on Earth Earth formed about 4.6 billion years ago from cosmic dust and gas, undergoing a process of accretion. 3.5 Billion Years Ago Development of Prokaryotic Life: The first life forms were prokaryotic cells, s...

ORIGIN AND HISTORY OF LIFE ON EARTH Brief History of Life on Earth Earth formed about 4.6 billion years ago from cosmic dust and gas, undergoing a process of accretion. 3.5 Billion Years Ago Development of Prokaryotic Life: The first life forms were prokaryotic cells, such as Archaebacteria and Eubacteria, thriving in anaerobic environments. 2.5 Billion Years Ago Oxygen Revolution and Prokaryotic Communities: Cyanobacteria played a crucial role in the Oxygen Revolution through photosynthesis.  2 Billion Years Ago Rise of Eukaryotic Life  541 Million Years Ago CAMBRIAN EXPLOSION It was when most of the major animal groups started to appear in the fossil record. 500 Million Years Ago Plant and Animal Adaptations Vascular plants adapted to terrestrial life, followed by arthropods and tetrapods, marking the transition from sea to land. 230 Million Years Ago EMERGENCE OF DINOSAURS  MAJOR EXTINCTIONS ACROSS EARTH’S HISTORY 66 Million Years Ago Rise of Early Mammals 4 Million – 2 Million Years Ago Hominid Development Started in Mid-20th Century Anthropocene Epoch The Geologic Time Scale of Earth's History -is the “calendar” for events in Earth’s history. UNITS OF GEOLOGIC TIMESCALE  PRE-CAMBRIAN EONS the longest eon and encompasses most of the Earth's history. PHANEROZOIC EON the most recent eon in Earth's history. Divided into 3 Eras namely: Paleozoic, Mesozoic, and Cenozoic.  Phanerozoic Eon PALEOZOIC ERA (541 million to 252 million years ago) “ancient life” It witnessed the emergence of fish, plants, insects, and the first terrestrial vertebrates.  Phanerozoic Eon MESOZOIC ERA (252 million to 66 million years ago) often known as the era of middle life and is famous for the dominance of reptiles, including dinosaurs.  Phanerozoic Eon CENOZOIC ERA (66 million years ago to the present) the era of recent life and spans from the aftermath of the Cretaceous- Paleogene extinction event to the present day.  Paleozoic Era CAMBRIAN PERIOD (541 to 485.4 million years ago) known for the "Cambrian” Explosion. Trilobites Brachiopods Mollusks, Other complex organisms with hard shells.  Paleozoic Era ORDOVICIAN PERIOD (485.4 to 443.8 million years ago) evolution of diverse marine invertebrates. The first vertebrates, jawless fish appeared. Ended with the Ordovician- Silurian Extinction  Paleozoic Era SILURIAN PERIOD (443.8 to 419.2 million years ago) colonization of land by early vascular plants First arachnids and centipedes appeared.  Paleozoic Era DEVONIAN PERIOD (419.2 to 358.9 million years ago) Called the "Age of Fish" due to the diversification of jawed fish. The first amphibians evolved. The first trees, emerged. Ended with the Late Devonian Extinction  Paleozoic Era CARBONIFEROUS PERIOD (358.9 to 298.9 million years ago) Amphibians were diverse, and the first reptiles appeared. Insects became more abundant and diverse.  Paleozoic Era PERMIAN PERIOD (298.9 to 252 million years ago) evolution of reptiles, including early synapsids. ended with the Permian- Triassic extinction event which is the largest extinction in Earth’s history.  Mesozoic Era TRIASSIC PERIOD (252 to 201.3 million years ago) Early dinosaurs First mammals Archosaurs Ichthyosaurs Plesiosaurs Ended with the Triassic- Jurassic Extinction  Mesozoic Era JURASSIC PERIOD (201.3 to 145 million years ago) known for the dominance of dinosaurs. The first birds evolved. Pangaea began to break apart, leading to the formation of separate landmasses.  Mesozoic Era CRETACEOUS PERIOD (145 to 66 million years ago) continued diversification of dinosaurs Flowering plants became widespread First true snakes appeared. ended with Cretaceous- Paleogene mass extinction event,  Cenozoic Era PALEOGENE PERIOD (66 to 23 million years ago) Adaptive radiation and diversification of Mammals Early primates appeared setting the stage for the evolution of monkeys and apes.  Cenozoic Era NEOGENE PERIOD (23 to 2.58 million years ago) Evolution of hominids (ancestors of humans). Evolution of grazing mammals like horses and elephants.  Cenozoic Era QUATERNARY PERIOD (2.58 million years ago to the present) Homo sapiens, modern humans, evolved and became the dominant species on Earth. continents continued to move and drift, affecting global climate and influencing the distribution of species  THEORIES ABOUT THE ORIGIN OF LIFE ABIOGENESIS RNA WORLD HYPOTHESIS PANSPERMIA also known as "chemical suggests that self- proposes that life, or evolution" proposes replicating RNA molecules at least the building that life emerged from played a crucial role in the blocks of life, may non-living matter early stages of life. have originated through a series of outside of Earth. chemical reactions.