The Precambrian Period: The Evolution Of Hard-Shelled Animals

Describe the important chemistry of early earth and how this may have given rise to life forms.

Fossils Tell of Long Ago uses accessible language and illustrations to aid all students in vocabulary and new concept growth. Explicit instructions, reading the book allowed to the class, and allowing conversation among individual students as they work through learning new words will aid ELL students in expanding their word knowledge. Furthermore, having ELL students translate new word to into their native language will help them activate their previous knowledge. Encouraging all students to be actively engage in learning words will ensure that ELL students and all students will gain knowledge and make connections to new words.

The evolution of that formation created the world we live in today. The earth has been in existence for a little over four point five billion years to be exact. The earth shares a story that we are still exploring. From its colorful coral reefs in bright and vibrant

The Cambrian Period marks the beginning of the Paleozoic Era. This period gets its name from a place in Wales where the first examples of this type of ancient life was found. The period lasted for nearly 53 million years, from about 543 million years ago until 490 million years ago. The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears. It was once thought that the Cambrian rocks contained the

Major Biological Event: During the beginning of the Precambrian era the first signs of life were found. They were basic, single celled organisms that use photosynthesis to make food. Later the organisms evolved into more complex species.

The Earth began several billion years ago, but just six thousand years ago history began to be recorded by people, and only 500 hundred years ago, European conquerors set off into the world, forever changing the balance of the entire planet. 225 million years ago the supercontinent began to drift apart and formed Eurasia Africa Australia and the Americas. It opened up the Atlantic and Indian Ocean as well as narrowing the Pacific Ocean. However land masses and coastal ranges developed at separate times . Basic geography of North America was formed 10 million years ago. The modern geography of the earth however was created by the great ice age 2 million years ago.

Throughout this first chapter, I think that I already believe that I will enjoy this book. At the start however, the book could not be any more boring. Rocks, rocks, and more rocks was all I could think of. I have always been one to enjoy learning new things as long as they are interesting subjects, but learning about older and younger rocks, how rocks move throughout time, and what can be discovered from those rocks, that doesn’t sound too interesting. I did learn something though. It was no real surprise to me that you can get so much information from rocks once I thought about it, but how they do it still surprises me.

Stromatolite forms and is the first organisms on the earth they were formed by very thin layers of single-celled organisms.

The Devonian period initiating approximately 416 Mya and culminating 359 Mya represents a geologic time period, which characterizes a major part of the Paleozoic Era. Traversing between the Silurian period (444 - 416 Mya), and Carboniferous period (359 – 299 Mya) the Devonian period epitomizes substantial modifications in the world's ecology and geography.

The oxygen revolution: During the Proterozoic, biotic system were being established, which gave rise to biomass of the prokaryotic organisms like the “benthic and planktonic photosynthesizing organisms” Due to the vast developing diversity of environment, organisms could well adapt to these various environments, which increased the input of oxygen on Earth. Hence, in order for the oxygen to be accumulated in the atmosphere, Iron and Sulfur like oxygen-sinks had to be depleted.

In the beginning, impacts of very large objects were very common, some as big as Mars or half the diameter of Earth. Collision of large bodies orbiting Earth played a role in its initial tilt of spin axis, the length of its day, direction of spin, and the thermal state of the interior. This violent bombardment continued for 3.9 billion years. Final composition of Earth had several crucial structural effects. Enough metal was present early on to allow formation of an iron and nickel rich core that is partially liquid. This enables a magnetic field that deflects some harmful radiation from reaching the surface. Enough radioactive elements are also present in the core to maintain long term heating which drives plate tectonics. At 4.5 billion years ago, Earth separated into different layers: an inner core (made of iron and nickel), a land layer of lower density material, and an early atmosphere of carbon dioxide and steam. At 3.9 billion years ago, surface temperatures dropped to a range where liquid water could be maintained. Liquid water makes up approximately 75% of the planet's surface today which is roughly what it was then. The most important requirement for life as we know it is the presence of liquid water. This is the one substance that can serve as a universal solvent - that is, it can dissolve and transport minerals and

The Mesozoic Era was from 248 mya to 65mya. The previous era was Paleozoic and the era after was Cenozoic. The cretaceous period: Upper 96-65 mya, high tectonic and volcanic activity. Primitive marsupials develop. Continents have a modern day look. Minor extinction 82 mya. Ended with large extinction, lower 146-98 the heyday of the dinosaurs. First crocodiles and feathered dinosaurs appear. Jurassic: 208-146 many dinosaurs there's, sauropods,Archaeopteryx, flowering plants,Ammonites, pterosaurs.Triassic: 248-208 mya first dinosaurs appear, mammals, and crocodile forms appear. True flies appear. The temperature in both land and water were much higher than during the Paleozoic period. Climates were more tropical in nature. There were desserts

Jurassic is a period of time with Dinosaurs, rodents and birds. There were also island seas consisting of sharks, sea monsters and blood-red planktons. The existing plants in that period were cycads, ferns and conifers. The Mesozoic era was about 245 million years ago to 65 years ago, so it almost lasted about 180 years in total. The Mesozoic era is divided into three periods of Triassic, Jurassic and Cretaceous. Mesozoic era means middle animals and it is the era, which the word’s fauna has changed from what is in the Paleozoic era and the most famous organisms of this era are dinosaurs. In the Mesozoic era, the extinction of more than 90 percent of species in the earth was observed and the reason behind it was mostly volcanic eruptions and climate changes. On the other hand, this era had massive changes that represented ecological niches and rise to new creatures such as rodent-size mammals and first dinosaurs. In Triassic, which was the first period of Mesozoic, the mammals and first dinosaurs existed. Later than that, the second period was Jurassic, which giant shaped dinosaurs and other kinds of dinosaurs were developed. Besides that the first flowering plants and primitive birds, with long teeth appeared in that era as well.

The Precambrian era laster 4600-541 million years ago. During this time, there were no plant life on the planet. Most of the things that were on the planet were rocks. The most common type of rock was Isua greenstone. Most rocks have been eroded away, subducted, or metamorphosed. During this time, the atmospheres and oceans were formed, plate tectonics began to build up continental masses. The air during this time was mostly made up of water vapor, carbon dioxide, and nitrogen. Later on, oxygen was formed from early animals taking in carbon dioxide and releasing oxygen. Scientists know this because oxygen was formed with iron, forming iron oxides (rust); after there were was no more iron to mix with oxygen, so it would

The conditions on early Earth consisted of large amounts of volcanic activity; heat, ash, dust and gases in the atmosphere, anoxic, massive oceans existed but only small land masses above the water surface, no ozone layer and violent electrical storms were common. There is evidence shown that the Earth contained inorganic molecules during this time. As a result