Our planet has changed a great deal in its 4.6 billion years of life. Earth’s climate, tectonic plates, and organisms are constantly evolving as time goes on. 4.6 billion years is a very long period of time to study in-depth and it would be too confusing to organize all the events in earth’s geological and biological history into one division of time, so scientist have split them up in order to better organize and understand how earth was like at particular periods of time. We’ll start at the beginning, 4.6 billion years ago, at the beginning of the Hadean Eon. The inspiration for the name of this eon came from the conditions of earth at the time. Earth was nothing more than a large magma ocean of molten rock material. It was very hot and unable to sustain life, therefore it earned the name Hadean, originating from the Greek god of death and the underworld, Hades. These are the reasons why I also chose to use an illustration of an ocean of magma, and also a skull and crossbones to represent this eon on my poster. There were no fossils of living organisms from this eon, therefore it hasn’t been divided into further sections of time. Directly following the Hadean Eon came The Archean Eon, which began 3.8 billion years ago. This eon is know best for its high amounts of volcanic activity, hence the illustration of a volcano on my timeline. There were no large continents on Earth at this time, but there were small fragments of continents dispersed across the globe. These mini continents were the “seeds” of larger continents that were to come later on. One significant detail about the Archean Eon was that it was the period of time where life first emerged on planet Earth. During this time, oxygen was not present in Earth’s atmosphere. Instead, the toxic gases methane and ammonia, byproducts of volcanic activity, filled the air. The only life forms on earth at this time were microscopic bacteria that could survive without the presence of oxygen in Earth’s atmosphere. After the Archean Eon ended 2.5 billion years ago, came the beginning of the Proterozoic Eon. I chose to draw a supercontinent and simple bacteria to represent this eon because during this time on earth, massive continents had just began to develop and bacteria were beginning to evolve with more structural complexity. Rodina, a supercontinent that included almost one-hundred percent of the land on Earth at the time, formed during this eon. Scientists believe that earth was completely covered in ice due to the fact that large glacial deposits have been found dating back to this eon. During the Proterozoic, approximately one billion years ago, trace fossils of simple single, and multi-celled eukaryotes, with complex organelles, have been found. The eon we are currently living in today is the Phanerozoic Eon, which started approximately 542 million years ago following the end of the Proterozoic. The beginning of this eon began with explosion of biodiversity, as many new creatures emerged on Earth for the very first time. Even though it is the youngest of the four eons, the Phanerozoic Eon had had the most variety of life forms, therefore it has been divided into twelve periods of time. The first period of the Phanerozoic Eon was the Cambrian Period, beginning 542 million years ago. This is where metazoans, or multi-celled organisms, began to appear. These organisms included worms, jellyfish, coral, Bilaterians, and the very strange and still poorly understood creatures of the Ediacaran family, like the infamous Hallucigenia. I chose to use a trilobite to represent the Cambrian Period because it was a very common anthropoid swimming in the vast oceans during this time. During the Cambrian Period most of earth’s land was located below the equator in the Southern Hemisphere. Though there was land present during this period, there were no existing land organisms. The next period was the Ordovician Period that began 488 million years ago. This period saw the origin
The Permian Triassic Mass Extinction
The Permian Triassic extinction was an event of cataclysmic disaster and almost the
extinction of all species on planet earth. The Permian Triassic extinction is said to have occurred
millions of years ago, geologist have estimated that its occurrences happened about 248 million
to 286 million years ago. This rare occurrence of events proceeded the Triassic geologic periods
and the Paleozoic and Mesozoic eras. This mass disaster…
Running head: MASS EXTINCTION
History of Life - Mass Extinction
Western Governor’s University
QXT2 ID Biological Science
March 13, 2015
History of Life - Mass Extinction
More than 99 percent of all species that have ever lived are now extinct. Usually, extinctions happen gradually, but several times in Earth’s history mass extinctions wiped out entire ecosystems. During these events, some biologists propose, “many species became extinct because their environment was collapsing…
Mass extinction has impacted our earth's evolution tremendously. From as far back as 500 million years ago during the Cambrian period, to as close to us now 65 million years ago during the Cretaceous-Tertiary extinction event, and all 3 events in between have affected the animals and plants surrounding our planet gigantically. Mass extinction is when there is a rapid decrease of animals and plant species on earth due to the earth's natural disasters…
to slow in the future.
Fast environmental changes typically cause mass extinctions. One guess is that 1%-3% of the species that have existed on Earth are still alive today
Since life began on Earth, five major mass extinctions and several minor events have directed to huge and quick drops in biodiversity. The Phanerozoic eon (the last 540 million years) marked a speedy growth in biodiversity via the Cambrian explosion—a period during which the common species of multicellular phyla first appeared. The…
We all studied the extinction of dinosaurs in middle school. We know that, two hundred fifty million years ago, more than 90% of the planet species became extinct. There have been five major mass extinctions during the life history of planet earth. Scientists now agree that we are experiencing a sixth major extinction. The big difference between the older events and now is, “unlike earlier extinctions, this one results from the work of a single species, Homo sapiens. We are relentlessly…
associated with a mass extinction event. A shift can occur due to a decrease in plant production following a meteor impact or from a large decrease in sea level that reduces shelf area, exposing the shelf and its accumulated organic carbon to erosion. There are sections examined in the Alps of Italy and Austria that actually show a gradual change in the C-13 content of marine organisms across the PTB. These sections show no dramatic shifts that can be associated with a mass extinction. Thus as you can…
their extinction and how their extinction opened the door for humans.
One well known theory that scientists believed made the dinosaurs go extinct is the asteroid theory. It is believed that an object, ten kilometers across, struck off the coast of the Yucatan Peninsula sixty-five and a half million years ago (What). The result of that would be a huge explosion that would throw dust clouds into the sky and darken the planet (Who). Also, massive…
History of earth is divided into segments of time. Eras are subdivided into periods, each period is characterized by specific animals, plants, climates, positions of continents
-precambrian- single-celled organism
99% of species that have ever lived are now extinct
boundaries between periods are marked by extiniction events-types of fossils in one layer disappear in the next
mass extinctions- extinctions that separate the eras…
19. Explain how the extinction of most of the dinosaurs affected mammalian evolution.
I. Biology and Society: The Sixth Mass Extinction
1. Over the past 540 million years, the fossil record reveals five periods of extinction when 50–90% of living species suddenly died out.
2. Our current rate of extinction, over the past 400 years, indicates that we may be living in, and contributing to, the sixth mass extinction period.
3. Mass extinctions pave the way for the evolution…
Prehistoric sea monster- found!!
Alexi Singh - February 25, 2014
Thalattoarchon Saurophagis A.K.A “lizard-eating sovereign of the sea” Was at least 8.6
meters long and lived about 244 million years ago, during the Triassic Period. The beast was
an early ichthyosaur (an extinct marine reptile of the Mesozoic era resembling a dolphin,
with a long pointed head, four ﬂippers, and a vertical tail.) part of a group of reptiles that
prowled the seas during the time of the dinosaurs…