Evolution: Exploring Earth's History PDF

EVOLUTION Exploring the changes of the Earth throughout time 2ND SEM: MODULE 2  Earth is the only known planet to have sustained and cater life. But have you ever wondered how did life begin on its surface? What are the features and characteristics of the first life on Eart...

EVOLUTION Exploring the changes of the Earth throughout time 2ND SEM: MODULE 2  Earth is the only known planet to have sustained and cater life. But have you ever wondered how did life begin on its surface? What are the features and characteristics of the first life on Earth? Where and when did exactly life begin? Are humans the first life found on Earth? If not, when did humans begin to populate the Earth? What are the organisms that walked before humans and with humans on Earth? Lesson Objectives: Describe general features of the history of life on Earth, including generally accepted dates and sequence of the geologic time scale.  Introduction The Earth is covered with thick blanket of ice, lots of volcanoes and high mountains, large organisms roamed the land, the atmosphere did not have high oxygen content, asteroids/meteors frequently hit the surface, the lands moved a lot or the continents were a little closer to each other, volcanic eruptions, little bit warmer, plats were bigger ammonia gas oxygen gas nitrogen gas water vapour and humans were not yet around. The Earth’s history is divided into eons, eras, periods and epochs. Geologic Time Scale It is a record of the life forms and geological events in Earth’s history. Scientist developed the time scale by studying the rock layers and fossils worldwide.  c EON Largest division of geological time scale; half billion – nearly 2 billion years ago.  The Precambrian Eon (Hadean, Archean, Proterozoic Eon) Covers approximately 88% of the Earth’s history. 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. Molten rock cooled down to form the earth’s crust and with that, the gases also changed providing a cooler temperature composed mostly of nitrogen.  The Precambrian Eon c (Hadean, Archean, Proterozoic Eon) Single-celled cyanobacteria to exist. Tiny, sessile soft-bodied sea creatures exist in Proterozoic Eon. Coronacollina acula - sponge-like fossils that show the existence of hard body parts and spicules. Movement of tectonic plates forming the supercontinent Rodinia in Proterozoic Eon. Earth’s core and atmosphere cooled down. Production of oxygen of the primitive cyanobacteria cause a drastic change in the chemical composition of the Earth’s atmosphere. Domination of aerobic eukaryotes, the first multicellular organisms.  c ERA Division that span time periods of tens to hundreds of millions of years. Paleozoic Mesozoic Cenozoic  c PERIODS Division of geologic history with spans of no more than 100 million years  Paleozoic Era Known as “Old Life” (540 – 300 million years) Divided into 6 periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Break-up of supercontinent Rodinia into continents Gondwana and Lauresia. Sea levels were very high. Began with a spectacular burst of new life – known as Cambrian Explosion. Cambrian Period (544 – 505 MYA) Primitive animals called sponges evolved. Small ocean invertebrates called trilobites were very abundant. Appearance and/or diversification of mineralized algae of various types (coralline red algae and dasyclad green algae). Cambrian period ended by lack of oxygen combined with poisonous hydrogen sulphide killed off many Cambrian animals. Ordovician Period (505 – 440 MYA) Best known for its diverse marine invertebrates. First vertebrate fish called ostracoderms (jawless fish). Plants invaded the land at this time. Earth experienced a milder climate. Massive glaciers formed. Mass extinctions due to dropping of sea levels in which 60% of all marine invertebrate genera and 25% of all families went extinct. Silurian Period (443.7 – 416 MYA) Evolution and diversification of fish. Coral reefs made their first appearance. First evidence of life on land is preserved (relatives of spiders and centipedes) The earliest fossils of vascular plants. Melting of large glacial formations. The extinction was a most likely a result of global cooling and reduced sea levels. Devonian Period (419.2 – 358.9 MYA) Known as “Age of Fishes”. Tiktaalik roseae, earliest known tetrapod is considered to be the link between the lobe- finned fishes and early amphibians. Lycophytes, horsetails and ferns formed Earth’s first forests. Archaeopteris were the first successful trees. Reproduction was by male and female spores are precursors to seed-bearing plants. Ends with a cataclysmic extinction event, particularly devastating to nearly 70-80% of warm-water marine communities. Carboniferous Period (359.2 – 299 MYA) Age of Amphibians Famous for its vast swamp forests that produced the coal from which the term Carboniferous, or "carbon-bearing," is derived. Collision of Laurasia and Gondwana to form the supercontinent Pangaea. Amniotes, the ancestors of modern reptiles, birds, and mammals, evolved. Insects grew to much larger sizes due to the high oxygen levels. The climate changed from warm and humid to more glacial conditions. The CRC was caused by a major global environment change. Permian Period (298.9 – 251.9 MYA) Land plants evolved from ferns and seed ferns to conifers. Reptiles evolved into three distinct groups: the cotylosaurs, the pelycosaurs, and the therapsids Insects reached their highest diversity of high-level forms of all time Major land masses combined to form supercontinent Pangaea. Extreme temperatures, dry climate. Plants and animals evolve. Ended with mass extinction Permian Period (298.9 – 251.9 MYA) Permian Extinction – the worst and massive extinction event in the planet's history, is estimated to have wiped out more than 90% of all marine species and 70% of land animals. Series of volcanic eruptions blocked the sun, causing a significant drop in temperature. Sudden warming and cooling.  Mesozoic Era Started 245 million years ago and lasted for 180 million years. Known as the “Middle life” Age of Reptiles and Age of Dinosaurs Subdivided into 3 periods: Triassic, Jurassic and Cretaceous  Mesozoic Era Started 245 million years ago and lasted for 180 million years. Known as the “Middle life” Age of Reptiles and Age of Dinosaurs Subdivided into 3 periods: Triassic, Jurassic and Cretaceous  Triassic Period First dinosaurs branched off from reptiles. Huge seed ferns and conifers Pangaea started to separate into Laurasia and Gondwanaland. Ended with mass extinction.  Jurassic Period “The Golden Age of Dinosaurs”; earliest bird evolve form reptile ancestors. Mammals evolve Flowering plants and new insects appeared Earthquake and volcanic activities are intense.  Cretaceous Period Dinosaurs reached their peak in size. Earth’s overall climate was warm. By the end of cretaceous, continents were close to their present locations. Ended with dramatic extinction of dinosaurs thought to be brought about by the collision of an asteroid or comet with Earth.  Cenozoic Era “Recent life”; started more than 65 million years and continues up to the present. “Age of Mammals” Paleogene Neogene Quaternary The formation of mountain ranges Animals had to adapt with the rise and fall of the oceans. Tertiary Period (65-1.8 MYA) Earth’s climate was warm and humid. Mammals evolve and increase in size. Primates evolved Modern rainforest and grasslands appeared Widespread flowering plants and insects. Quaternary Period (1.8 MYA-Present) Earth’s climate was cool Sea level fell because water froze. Some mammals, like mammoths adapt to the cold.  EPOCH Smallest division of the geologic time scale.