Classify Each Event in the History of Life into the Appropriate Eon or Era

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1. Hadean eon

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Origin of Earth.

2. Archaean eon

Oldest fossils of cells (prokaryotes) appear.

3. Proterozoic eon

Oldest fossils of eukaryotic cells appear. First invertebrates appear.

4. Paleozoic era

The Cambrian explosion, first tetrapods and insects appear.

5. Mesozoic era

Dinosaurs evolve and radiate. Origin of mammals.

6. Cenozoic era

Humans appear. Major radiation of pollinating insects.

The Hadean Eon.
The Hadean Eon.

Hadean era

What is the Hadean Eon?

The Hadean eon is the earliest period in Earth’s history. The Earth formed 4.5 billion years ago, but scientists think that meteors and asteroids were crashing into it, which created a lot of extreme temperatures and pressure on the planet’s surface. In Greek mythology, Hadean refers to Earth being in the “Hades zone” or “hellish zone,” named for the Underworld.

When was the Hadean Eon?

The Hadean eon began about 4.5 billion years ago (00.5 billion years ago) and lasted for about 500 million years.

The Earth was surrounded by giant rocks, which bombarded it constantly, causing extreme temperatures and volcanoes on the surface of the planet itself, sometimes reaching up to 1000 degrees Celsius (1832 degrees Fahrenheit).

What happened in the Hadean Eon?

There were numerous impacts during this time, which caused devastating volcanoes that would later cool into the Earth’s primordial crust. A survivorship curve explains the history of life in a very understandable way.

The Earth was just being made and was still a very hostile place. There were massive volcanoes and earthquakes everywhere. The whole planet was in danger of being utterly destroyed. The key events include:

1. Heat source

The Earth was still very hot during this time. Many of the remains of this time in the rocks would be hot, volatile materials (volatiles are unstable compounds that quickly break down). There were very high pressures, which means that most rocks don’t move with enough ease to have a chance of breaking. Volcanoes were happening all over the place, and they were responsible for a lot of impacts and craters on Earth.

2. Magnetic field

It was the first step for life to persist on Earth. The conventional currents produce a geodynamo, a magnetic field that shields the Earth from the solar wind.

3. Formation of the crust

The volcanic activity produced an ocean of molten rock under a layer of nickel-and-iron rich “asthenosphere.” (asthenosphere is just a more technical term for the molten layer on top of the mantle) The Earth’s surface cooled enough to solidify into a crust, and then it was only over time, as the planet continued to cool, that plate tectonics was possible.

4. Moon formation

The last thing to happen in the Hadean Eon was forming the Moon. Early in the Hadean Eon, an object nearly the size of Mars (called Theia) struck Earth at a glancing angle, sending a cloud of debris into space. Over time, this debris came together and formed the Moon we know today.

When did the Hadean Eon End?

The Hadean eon ended at 0.51 billion years ago. Scientists aren’t entirely sure of the exact date, but they are sure that the end of the Hadean eon was when the asteroid hit Earth (known as the Giant Impact on Earth). This allowed Earth’s mantle to cool and begin forming tectonic plates (see above). Eventually, plate tectonics would be responsible for forming mountains, lakes, and oceans on Earth.

What major event occurred during the Hadean Eon?

The formation of the Moon (late in the Hadean eon) created a change in the Earth’s orbit. This change would cause a significant amount of material to be lost, making its way into space. Scientists think this object that hit the Earth was a small moon (known as Theia) and that it will slowly come together into an object known as Nemesis. The Moon is essential to Earth because it helps keep our planet cool and helps regulate the amount of water that comes in and out.

What was the climate like in the Hadean Eon?

The Earth’s surface temperatures were much higher than today. The temperature of the planet was hot enough that it caused a lot of rock and metal to melt, which then flowed into oceans. This created a vast amount of materials for volcanoes to erupt.

What was the Archaeon Eon?

The archaeon eon is the latest period in Earth’s history. It is when most of Earth’s current life forms are thought to have emerged. The “archaeon” refers to a life that has been around since the beginning of our planet. The archaeon eon lasted from 2.5 to 4 billion years ago.

What makes the Archaean Eon unique?

The archaean eon was unique for a variety of reasons. It was the first time that complex life began to show itself on Earth. This is because the archaean eon is when all of the current tectonic plates were formed. Until this point, there were no real continents that could sustain life.

The Archaean Eon also marked a shift in the Earth’s climate and atmosphere. The Earth’s atmosphere was very different during the archaean eon. In particular, there was a lot of methane in the atmosphere, which is known as an ozone-depleting gas today. This methane would have been so high in the atmosphere that it would likely kill all animals and plants if it weren’t for a bug that ate holes in the methane clouds.

The last unique thing about the archaean eon is that it was when photosynthesis began to appear on Earth.

What were the major event(s) of the archaean eon?

The major events include:

  • Oceans and Continents

The archaean eon is the earliest period in the history of the Earth during which continental drift and the formation of oceans occurred. By the end of this era, a fully-formed crust and hydrosphere had existed for more than 2 billion years.

  • Banded Iron Formations

The banded iron formations of the archaean eon are iron formations (rocks containing iron). They contain alternating layers of iron-rich and iron-poor strata; the purpose of this alternation has not yet been completely determined. Scientists think that their formation occurred hundreds of thousands to millions of years after the sediments in which they formed were created.

  • Ozone Layer

There is evidence that the archaean eon was the era during which Earth formed an ozone layer. The evidence comes primarily from the metal molybdenum used in enzymes for metabolizing oxygen. However, other indicators, such as oxygen-isotope ratios in sediments, indicate high levels of ozone and large amounts of UV radiation on Earth during this time, and there are no known minerals that could have been involved in reducing this amount of UV radiation except for ozone itself.

What was the climate like in the Archaean Eon?

The climate of the archaean eon was different in a variety of ways. The most prominent difference is that there was more carbon dioxide in the atmosphere than oxygen. This meant that the atmosphere would have been capable of producing a lot more methane and ammonia. Another difference is that there were no glaciers on Earth during this period. 

Which Eras are in the Archaean Eon?

The Archaean Eon is divided into four eras: the Mesoarchaean, Eoarchean, and Paleoarchean, Neoarchean.

Why wouldn’t humans be able to survive in the archaean eon?

Humans probably wouldn’t survive in the Archaean Eon because they wouldn’t have a climate to live in; they wouldn’t have any oxygen, and most likely, they wouldn’t be able to eat as there would be no plants or animals.

Proterozoic eon

What is Proterozoic eon?

The Proterozoic eon is a geological eon representing the time just before the proliferation of complex life on Earth that began about 2.5 billion years ago, at a time when Earth’s atmosphere was changing from one mainly containing ammonia and methane to the oxygen-rich atmosphere that we have now.

How long was the Proterozoic Eon?

The Proterozoic eon lasted from 2.5 billion to 540 million years ago.

Which major Events define the Proterozoic Eon?

1. Increased oxygen

One of the biggest evolutionary developments at the end of the proterozoic eon was an increase in oxygen levels and a greater diversity of organisms. This paved the way for more complex ecosystems and animals to evolve eventually.

2. The formation of Pangea

By the end of the proterozoic eon, our continents had formed into a single large continent called Pangea, which surrounded a single ocean called Panthalassa. All of the continents were in roughly their present positions.

3. Photosynthesis begins

Photosynthesis, in which plants convert carbon dioxide into oxygen and sugars, had begun by the end of the proterozoic eon. This allows for more complex ecosystems to flourish and for animals to evolve.

What did the Earth look like during the Proterozoic Eon?

  • The atmosphere and oceans were very different in the proterozoic era. There was much more atmospheric carbon dioxide, which was a byproduct of photosynthesis. There was also more methane in the atmosphere, and it may have been the reason why there were no glaciers. Although there were oxygen molecules in the atmosphere and oceans, they were bound to other molecules, so no free oxygen entered Earth’s atmosphere or water.
  • The continents were still forming during this period.
  • The Earth’s interior was also much different during the proterozoic eon, as the continents were still being formed. Consequently, the structure of Earth’s surface rock changed significantly, with a more significant proportion of younger, more sedimentary rocks forming around the base level.

What happened in the Proterozoic Eon?

  • Formation and break-up of supercontinents

During the Proterozoic, there were several supercontinents. First, larger continents had formed together before the Proterozoic, and the continents all surrounded a single ocean called the Panthalassic Ocean. Then, about 1 billion years later, Pannotia formed from Baltica, joining with Laurentia and then with what would become Amazonia and West Africa. This supercontinent existed for about 100 million years until it broke up again in the Mid-Proterozoic collision with Rodinia to form Nuna.

  • Life and oxygenation of the atmosphere

Before the Proterozoic, there was very little oxygen on Earth. During the Proterozoic, this changed. By about 2.4 billion years ago, stromatolites began to form, and oxygen levels in the atmosphere rose from 0.01% to about 1%. This allowed for more complex organisms, such as multicellular life, to evolve and for ecosystems to become richer and more diverse.  

How long did the Paleozoic Era last?

289 million years.

What does the Paleozoic Era mean?

This is the period when rocks got deposited. The Paleozoic era produced some of the most diverse fossil records of life on the Earth. The fossils in these rock layers show many animals—both extinct and living—and plants, including primitive vascular plants (the ancestors of modern vascular plants), that existed on Earth at that time. Because these rock layers also preserve so many fossils and because they are so extensive, paleontologists can study how life evolved over time

Which event characterized the Paleozoic Era?

It was characterized by two major events, the Cambrian explosion, and the Permian-Triassic extinction event.

  • The Cambrian explosion – It is the point in history when most of the modern phylum first appeared in the fossil record. This event brought forth animals with shells, exoskeletons, and limbs – all characteristics that define modern animals. They ranged from small to large in body size. But even more critical appeared new lifestyles and new modes of feeding, mobility, and sensory perception. The Cambrian Explosion began 540 million years ago and ended approximately 510 million years ago.

What were the results of the Cambrian Explosion?

Animals and plants evolved quickly from simple to complex. 

  • The Permian-Triassic extinction event – It began with a massive volcanic eruption in Siberia, which eventually covered about 80% of Earth’s land area and released more than half the carbon and 96% of the nitrogen to be released since life began. This event is often referred to as an “extinction shock. The Earth’s atmosphere and oceans change drastically. The extinction of plants and animals at the end of the Permian is often blamed for Earth’s next mass extinction event, the K-T extinction, which occurred about 65 million years ago.

What periods are in the Paleozoic Era?

It had six periods:

1. Ordovician period

2. Silurian period

3. Devonian period

4. Carboniferous period

5. Permian period

6. Triassic period

When did the Paleozoic Era End?

It ended around 252 million years ago.

Mesozoic era

What is the Mesozoic Era?

The Mesozoic era was the period during which the dinosaurs ruled. It begins with the Triassic period and ends with the Cretaceous period. The Triassic-Jurassic extinction event marks the boundary between them.

What is the Textbook Theory that brought the end of the Mesozoic Era?

The theory that brought the end of the Mesozoic Era is a massive asteroid that collided with Earth in the present-day Yucatan Peninsula. It spewed dust and debris into the atmosphere, cooling and darkening the Earth’s surface. That darkness killed off many plants and animals living on land and in the sea. Half of all plant species disappeared within about a year after the impact, which led to droughts followed by fires that scorched large areas of land and killed many more animals.

What is the earliest and most recent period of the Mesozoic Era?

The earliest period was the Triassic 245 million and the most recent was Cretaceous 146 million years ago. 

What is the time range of the Mesozoic Era?

251 million years ago to 65 million years ago

What is One Event That Marks the End of the Mesozoic Era?

The Cretaceous-Tertiary extinction event is the arrival of a comet or large meteorite on Earth about 65 million years ago. The collision and the subsequent effects severely affected the biosphere, causing the extinction of the non-avian dinosaurs and other large reptiles, and many species of mammals, plants, and insects. 

Cenozoic Era

What does the Cenozoic Era mean?

Cenozoic is the present-day era of geological time from 66 million years ago. It encompasses the time since the extinction of the dinosaurs.

How long is the Cenozoic Era?

The interval of the Cenozoic era is 66 million years ago to date.

Which is a description of the Cenozoic Eon?

The Cenozoic era is a period from 66 million years ago to today. It includes every period since the extinction of the dinosaurs, up until the earliest humans first walked on the planet. Earth’s climate has become warmer and more stable over time, but it hasn’t always been so.

What was the major climate during the Cenozoic Era?

During the Cenozoic era, Earth’s climate advanced and retreated in a series of climatic cycles that are called glacial cycles. Both cooling and warming periods have occurred during the glacial cycles. The cooling period is called a glaciation, when glaciers encase large land areas from sea level to at least 4 kilometers above sea level. The warming period is called interglaciation.

History of life covers a lot of things. We can even use statistics to explain about the various eons. Our do my statistics homework for money service will assist you with any form of help you may require.

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Categories: History