Notes V1 to V9

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Frida Galvan GEOL-1404-V01 Mrs. Williams November 3, 2022 Brief Notes V1 It is hard to imagine the 4.5 billon years of the Earth’s age, but geologists used a football field to explain what happened in all the 4.5 billon years. For the first few hundred million years, the earth was bombarded with rocks from outer space, in 4.3 billon years ago, it started to calm down and at 3.8 billion years ago life begins. It wasn’t human life, it was simple single cell life vesting from the ocean, the cells are trying to adapt to find new ways to get energy. Photosynthesis starts at 3.5 billion years, the air it is mostly carbon dioxide and nitrogen, but green cells start making oxygen. At 2.3 billion years ago, oxygen starts creating an atmosphere, we are in the middle age of the earth and now the earth has the atmosphere where humans can breathe. For the next billion and a half years cells start working together and multi-cellular begins, this started to happen 800 million years ago. At 600 million years ago, the earth has a ozone layer, an at this time it starts to be an explosion of diversity where fungi, sea anemones, and molluscs start to grow. At 530 million years ago, animals start to exist in land and in the ocean animals appear too. At 176 million years ago, mammals and dinosaurs are found, every single specie appears in different timelines. In 66 billion years ago a mass extinction happens and it kills 75% of all species, but life it is still there. In 200 thousand years ago, humans are found that look like us and, in the end, there is civilization, agriculture, and science. V2 Alfred Wegener spent years traveling the world, collecting geological and fossil evidence to argue that all the continents were once connected. In the 1950s and 60s, researchers studied the bottom of the ocean and found out that there was an enormous mountain range running through the middle of the Atlantic, eventually they found out that these undersea mountain rages are all around the world and are called mid-ocean ridges. Seafloor spreading and subduction are 2 primary mechanisms behind plate tectonics. The process of continents coming together and splitting apart is known as the supercontinent cycle. There are a lot of predictions of how the earth might look because the supercontinent cycle would happen again maybe in 50 million years, but there are a lot of theories. V3 Fossils are remnants or impression of ancient organisms that are naturally preserved in stone. There are hundreds of fossil types, but they are often grouped into 2 major categories body fossils which are preserved in plants and animals, and trace fossils which are records of an animal’s behavior such as footprints. These 2 categories form the fossil record, a primary account that tells the story of life on earth through stone. Fossilization or the process of preserving organisms in stone can occur in many ways, depending on if organisms are altered during the fossilization process. Fossilization that does not alter a specimen can preserve its original form and texture, like frozen, tar pits, or mummified. One special case involves trapping organisms often insects in amber in tree sap or resin in a protective seal around the entrapped organism. Other fossilization methods change the specimen as it is being preserved its carbonization which transforms soft tissues into thin black films of carbon. One of the most

common types of fossilization is permineralization, it happens when minerals from water or the ground enter the pores of dead plant or animal material over time attach themselves and build a crystalline network in the empty cavities, hardens and turns into stone. V4 At the beginning of the Paleozoic, living things were extremely simple and not very dynamic, life was fragile and vulnerable. The Paleozoic was the most chaotic of the three eras of our eon with constant revolutions in life marked by catastrophic extinctions. For the first three and a half billion years that life existed things were simple, all living things were in the oceans and most of them couldn’t move on their own. Until 541 million years ago, the Cambrian explosion was the result of a whole bunch of environmental triggers. In the early Cambrian oxygen levels ramped up allowing life to flourish, and at oceans erosion allowed animals to develop shells and exoskeletons which led to the formation of new body like calcified hard parts, flexible limbs and eyes. The Cambrian ended 488 million years ago in a mass extinction of trilobite and mollusk species. In the Ordovician period a burst of geological activity meant the creation of new continents and islands and with the changes in sea levels and oxygen the appearance of ostracoderms and changes for the cephalopods of new lengths like giant cameroceras. During this time on land the very first land plants sprouted but the massive number of plants took much carbon dioxide that the earth’s temperature plummeted into an ice age that wiped 86% of marine species. In the Silurian period life was able to recover and with a warm climate plant too, ostracoderms developed spines and horns. By the end of the Silurian 419 million years ago, a new type of fish learned to defend himself, the entelognathus appeared in the seas with the biting power to tackle prey that other jawless fish couldn’t handle. The Silurian ended with the extinction events likely by the drop of sea levels. In the Devonian period the earliest sharks made their first appearance but the main was the placoderms, and at land the arthropods started to diversify with the first insects, terrestrial arachnids emerging, trees arose creating the major ecosystems on earth. This period ended by another mass extinction from 375 to 358 million years ago by the drop of oxygen levels in the seas. In the carboniferous period the oxygen ramped up along with humid and a warm climate which allowed dense forests and swamps to spread across the continents. The oxygen was a plus for the arthropods which got huge, tetrapods began to lay their eggs with shells to protect them from drying out. The continents began to merge into a single supercontinent, the landmass was so big that it ended in a severe drop in humidity and temperature that wiped out the carboniferous forests about 305 million years ago, by the end of this period much of the forests were replaced by a desert at the heart of the continent with extensive glaciers in the southern hemisphere. In the Permian period, the climate got hotter and drier and stem-mammals and reptiles who survived the carboniferous were forced to adapt to harsher conditions. The stem-mammals grew even stranger with the sabre-toothed gorgonopsids hunting hippo like omnivores but ended 252 million years ago probably caused by volcanic activity and climate change. The Permian Triassic extinction event nearly spelled doom for life on earth because 96% of marine species including sharks, fish and all the trilobites were wipe out.

V5 When dinosaurs die the skeleton gets buried in mud over million of years more layers of land and on top mud, sand, and even volcanic ash. The layers turn into hard sedimentary rocks while water seeped into the bones with left behind minerals turning the bones into stone and creating a fossil. Rocks that were once deep underground arose to the surface with a process called uplift, and with wind and water eventually the fossil skeleton were exposed and became visible in the surface. V6 A quarter of a billion years ago, the survivors of a near apocalypse emerged and came to dominate the earth. The reptiles grew to become some of the largest forms of life ever to stomp, swim, and soar across the planet. The animals and plants that diversified played key roles in the planet’s future. Over the years, they adapted to a rapid changing world but even though they grew to immense sizes and dominated all environments many reptiles couldn’t adapt to changes and their reign ended. The Mesozoic era began 252 million years ago in the aftermath of the most destructive mass extinction of all time, the great dying. In the early Mesozoic, earth’s landmasses had almost finished merging into a single supercontinent called Pangea. In the Triassic period, the planet was populated only by the survivors of the Paleozoic marine reptiles were mostly amphibious, but they developed fully aquatic traits, and at land the archosaurs started to breath more efficiently in the low oxygen atmosphere and take advantage of this new world. The last remnants of Paleozoic swept away when Pangea began to break apart as north American drifted away causing a spike in volcanic activity that sent greenhouse gases into the atmosphere and raised global temperatures. In the Jurassic period reptiles reached its peak, at this time dinosaurs acquired adaptations and body changes at helped them eat the toughest plants of the Mesozoic. By 150million years ago the first paravian dinosaurs had wings but they were not very good fliers. In the late Jurassic one of the most famous forms appeared, the spiky ornithischian stegosaurus and the carnivorous allosaurus in north America. The breakup of Pangea was still happening, the sea levels rise, landmasses moved and led to a series of extinctions and ended the Jurassic period in about 145 million years ago. The cretaceous period was the longest period of the Mesozoic, it saw the most extreme changes recorded in flora and fauna. By 125 million years ago big predator coelurosaurs were roaming north America while yutyrannus was hunting in China and at the sky pterosaurs got much bigger and became the largest animals ever to fly. Titanosaurs became much more common on the southern landmasses, while in the north a group pf feathered coelurosaurs reached the rank of apex predator. By the late cretaceous many of the dinosaurs were the largest and most bizarre that existed. At the end of the cretaceous, ceratopsians were becoming less diverse probably because they were vulnerable to extinction, this period ended with the largest volcanic eruptions ever in history which wiped out the giant reptiles, marine reptiles like the ichthyosaurs and pliosaurs it drought the extinction of 75% of the world’s species. V7

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Huge volcanic eruptions pumped the air full of globe-warming carbon dioxide, with the continents locked together from pole to pole in the supercontinent of Pangea the earth was hot, flat, and very dry. Reptiles and mammal ancestors thrived in this sweltering land and dominated this landscape that was trying to recover from the Permian extinction. Starting around 234 million years ago the climate suddenly changed, the rain finally came and stayed for 2 million years ago. This period of intense rain killed many off the early reptiles, this time is known as the carnian pluvial episode and set the stage for new animals to take over the world. The dinosaurs existed in this time, but they were still looking for their place among the early reptiles and reptile like mammals. During this time a lot of large conifers and big coal forming plants developed which was a game changer for food supply for the dinosaurs. The reason it rained for 2 million years was because 235 million years ago a huge burst of volcanic activity in Alaska and British Columbia that lasted for 5 million years ago, the temperatures created a weather so warm and wet that rained finally reached Pangea’s vast interior. All that rain helped conifers spread and diversify to the pine trees, and by the time the rain ended the age of dinosaurs began. V8 In the Cenozoic era many organisms took shapes and behaviors that actually can be recognized, the mammals and reptiles we know appeared during this time and went to surprising changes. At the start of the Cenozoic era, 66 million years ago there was still a lot that we couldn’t recognize it was so warm that the whole world was full of tropical and subtropical forests even at the poles. The first 10 million years the world was still recovering from the K-Pg extinction, many terrestrial, ocean species, and even plankton were gone. During this Paleocene epoch plenty surviving forms of life began to fill them, the last remaining dinosaur’s birds had begun to diversify into a recognizable form and on the forest floor ungulate like mammals began to take over. By the middle of the Paleocene epoch animal life was on the rebound, it started to get really warm about 55 million years ago, the average temperature on land went up 5 to 8 degrees Celsius with marked the transition to the next epoch. The Eocene epoch started to get even hotter which was a good thing for animals that thrived in the heat like reptiles. During this time the true primates were starting to appear, the tiny omomyids then about 49 million years ago this warming trend shifted and the world began its long journey from a greenhouse to an icehouse. In north America and Europe, the changing forests caused problems for mammals that lived in the trees including the primates. By the late Eocene, all of the primates on those continents died out but also mammal groups started to show up in the fossil record like familiar rodents, odd-toed ungulates, and the simians that began to appear in the fossil record. The Oligocene begins around 34 million years ago when we start to see an early member of the group that includes the old-world monkeys and eventually apes. Ice sheets begun to form in Antarctica and another extinction event began to happen mostly in Europe known as the Grande coupure. The new world monkeys retained a lot of the traits of earlier monkeys like their small size and fruit-based diet while the larger old world monkeys began to have a different diet. The Miocene epoch begun with the mountain building era that continues today, while in Africa the first apes evolved from the old-world monkey. As the world continued to cool, forests began to shrink while grasslands spread. Apes continued to diversify and split off from the ancestors to humans. The ancestors of orangutans diverged from our lineage first

about 13 million years ago, the ancestors of gorillas were next, around 10 million years ago chimpanzees and bonobos, and around 7 million years ago when the Miocene ended 5.3 million years ago the lineage led to humans. The Pliocene involved a brief period of warming followed by an even faster drop of temperature, while our ancestors were taking over the expanding grasslands becoming a better runners and skilled hunters. By 2.8 million years ago a new genus homo appeared on the scene in the form of a lower mandible and started the quaternary era about 2 and half million years ago. V9 The Anthropocene epoch is an unofficial unit of geologic time used to describe the most recent period in earth’s history when human activity started to have a significant impact on the planet’s climate and ecosystems. The first appearance of the genus homo is characterized by barely recognizable influence from our early ancestors on the environment. Homo erectus appeared almost 2 million years ago at a time when the global climate changed making Africa drier and more open. Homo sapiens leaves ancestral Africa and spread in Eurasia and Australia less than 100,000 years ago, and Toba superuption in Indonesia that happened 72,000 years ago caused substantial regional impacts, and possibly a 1,000 year long global cooling episode. In 50,000 to 10,000 many periods of earth’s geological history define extinctions but, on this time, it was due to humans overhunting, north America lost 72% of its large mammals, south America 83%, Australia 88% by about 11,000 years ago. 40,000 years ago, the first cave paintings started to appear in Indonesian caves of human hands and pig-deer has the oldest ever found. The neanderthal extinction happened during a time when modern homo sapiens began to emerge in Eurasia, and by 11,700 marks the beginning of human action including all its written history, major civilizations and development of agriculture. 11,000 to 9,000 tribes make attempts to domesticate dogs, goats, and sheep, large settlement places started to emerge, extensive farming, rice production, the invention of wheel to transportation in 3,500 and so on becoming the world we know nowadays.