GenBio2-Lesson-2-ORIGIN-OF-LIFE-AND-DIVERSITY-Part-1.pptx

The Earth Through Time Lesson 2  Introduction What is Geologic Time Scale? The geologic time scale distinguishes Earth's history based on life-forms that existed at certain times since the planet's formation. The majority of these life forms are discovered as...

The Earth Through Time Lesson 2  Introduction What is Geologic Time Scale? The geologic time scale distinguishes Earth's history based on life-forms that existed at certain times since the planet's formation. The majority of these life forms are discovered as fossils, which are the remains or evidence of an organism from the geologic past that have been preserved in silt or rock. Without fossils, geologists might not have established that the world has a past that predates humanity. Precambria n LIFE (Hadean, Archean and Proterozoic eras) An Introduction to Geologic Time Scale  HADEAN ERA The Earth was transformed from a ball of gas and dust to liquid rock enveloped with hot, non-breathable gases mostly composed of carbon dioxide, nitrogen, and sulfur. The molten rock cooled down to form the earth’s crust and with that, the gases also changed providing a cooler temperature composed  ARCHEAN ERA Cyanobacteria and only tiny, sessile soft-bodied sea creatures exist. Fossils of Coronacollina acula, date back as far as 560 million years were recently discovered in South Australia.  ARCHEAN ERA Another recent fossil discovery may represent the earliest animal species ever found. While the validity of this claim is still under investigation, these primitive fossils appear to be small, one-cm  Proterozoic ERA The latter part of Precambrian life, the Proterozoic era, was greatly affected by the movement of tectonic plates forming the supercontinent Rodinia. The Earth’s core and atmosphere cooled down and brought about the Ice Ages. domination of aerobic eukaryotes, the first multicellular organisms. PALEOZOIC ERA An Introduction to Geologic Time Scale  PALEOZOIC ERA This era known as “Old Life”, started more than 540 million of years ago and lasted for more than 300 million years. This era is divided into six periods: Cambrian, Ordovician, Silurian, Devonian,  PALEOZOIC ERA Geological processes during this era began with the break-up of supercontinent Rodinia into continents Gondwana and Laurentia.  PALEOZOIC ERA As the Paleozoic progressed, glaciations created a global climate, but conditions warmed at the end of the first half of the Paleozoic, the landmasses began moving together. Eventually a single supercontinent Pangaea, was formed in latter third of the Paleozoic.  PALEOZOIC ERA Towards the latter part of Paleozoic era, however, the largest mass extinction in history also occurred, wiping out approximately 90% of all marine animal species and 70% of land animals. When the continents were rejoined as Pangaea, lower sea levels increased volcanic activity, and climate change are the possible causes of the Mesozoic ERA An Introduction to Geologic Time Scale  Mesozoic era This era is known also as the era of dinosaurs because its predominated by reptiles because of their ability to withstand dry climates. Gymnosperms were most abundant during this era because their seeds were protected to endure the dry weather.  Triassic period Pangaea still formed one massive continent. Pangaea experienced major temperature swings and was covered with large swaths of desert.  jurassic period a rise in sea levels which flooded coastal regions and hastened the break-up of supercontinent. With more coastlines, many areas experienced warmer, more stable temperatures, and a wetter climate.  cretaceous period carbon dioxide levels in the atmosphere had risen, trapping the planet’s heat. As a result, the planet was hotter- possibly up to 10 degrees Celsius warmer. Cretaceous period ended with a mass extinction event thought to be brought about by the collision of an asteroid or comet with Earth. cenozoic ERA An Introduction to Geologic Time Scale  Cenozoic era This era started 65 million years ago and continues up to the present time. It is divided into three periods: Paleogene, Neogene and Quaternary. The world’s great mountain ranges were built during this era.  cenozoic era The Himalayas were formed during sometime after the Indian plate collided with the Eurasian plate. The formation of these mountain ranges contributed to the cooling down of the climate in this era. Cenozoic era Marsupials Placental mammals  cenozoic era This era is the development and proliferation of perissodactyls and artiodactyls. During the later of this era, perissodactyl diversity declined markedly, but artiodactyls continued to diversify.  cenozoic era Many giant placental forms, like the sabertoothed tiger, giant ground sloths, woolly mammoths, inhabited the forests and the plains in the Pliocene epoch. It was also about this time that the first hominids appeared.  cenozoic era Many giant placental forms, like the sabertoothed tiger, giant ground sloths, woolly mammoths, inhabited the forests and the plains in the Pliocene epoch. It was also about this time that the first hominids appeared.  cenozoic era Paleolithic hunters are considered by the scientists as more likely the cause of the disappearance of these mammals. The rapidly improved technology of Paleolithic humans produced more efficient tools for hunting.  cenozoic era As climatic differentiation increased over the course of Cenozoic era, flora became more and