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Transcript of Precambrian Era
•Precambrian era which includes the Proterozoic eon and the Archean eon spanning about 2000 years each.
•That single celled organisms like blue-green algae and bacteria first appeared.
•Towards the end of the Archean eon the first multicellular, soft bodied animals began to emerge such as jellyfish, seapens, and worms
•The earliest multicelled animals that survived the Precambrian fall into three main categories: sponges, cnidarians and annelids.
•Sponges were organisms lacking a nervous system; they lived by drawing water through their bodies and filtering out food particles.
•Cnidarians, which included sea anemones, corals, and jellyfish, had sac-like bodies and a simple digestive system with a mouth but no anus. They caught food using tentacles.
•Annelids or flatworms had fluid-filled body cavities and breathed through their skins.
•It's thought the final stages of Precambrian time were marked by a global ice age. This may have led to widespread extinctions.
Precambrian animals Precambrian Events •Precambrian time represents most Earth's geologic history and covers nearly 90% of Earth's history.
•The oldest known fossil evidence dates to early in Archaean time.
•Despite of geological weathering and erosion , evidence of Precambrian time impacts dating almost 2.0 billion years ago have been found in what are now South Africa and Canada.
Facts • The Precambrian Era is Earth's first era of time. It began with the creation of the Earth around 4.6 billion years ago and lasted until 570 million years ago.
• The five major events of the Precambrian are:
1. The formation of the Sun and light.
2. The creation of the Earth.
3. The creation of the atmosphere through volcanic out-gassing.
4. The creation of the oceans.
5. The creation of life. This actual process remains open to debate as to how it all took place.
• After rainfall, the Earth's surface was cooled down and the rainwater was collected into low areas which formed oceans and seas.
• The Precambrian Era is divided into three periods: the Azoic, Archeozoic and the Vendian.
• Azoic period: the formation of the Earth, atmosphere and oceans.
• Archeozoic period: when first simple life forms such as bacteria and algae formed.
• Vendian period (last): witnessed the creation of simple organisms such as jellyfish and sea worms.
• All Precambrian life forms were simple multi-cell creatures. These life forms were blind, brainless and soft bodied creatures, in that they had no hard skeleton. •Encyclopedia.com. (2003). Retrieved October 21, 2012, from http://www.encyclopedia.com/topic/Precambrian_era.aspx
•National Geographic. (2012). Retrieved el 21 October 2012, from http://science.nationalgeographic.com/science/prehistoric-world/precambrian/
•Dinosaur Timeline Gallery. (n.d.). Retrieved October 21, 2012, from http://www.prehistory.com/timeline/precamb.htm
•Precambrian Era. (n.d.). Retrieved October 21, 2012, from http://www.kinderscience.com/precambrian_era.htm