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ETD 56 A. Draw and Label a timeline of earth's major eras B. Place on that timeline 10 of the biggest events in life's history and explain their importance
February 26, 2014 at 11:45am


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Sophie Wulfing
March 23, 2014 at 10:14pm

1.  Pre-Cambrian - oceans formed which gave rise to first bacteria doing photosynthesis.  This creates an atmosphere, which follows the first few Eukaryotas. This gives rise to multi-cellular life.  This kicked off the Cambrian explosion.   This begins the Paleozoic.  Vertebrates and land plants.  Land animals follow.  Next amphibians follow insects (whom they eat), then came the Permian Extinction, which gve rise to the Mesozoic Era (the dinosaurs), which didn't need to live in water, ewre very mobile.  Next flowering plats and mammals.  Next the CT where the giant asteroid hit the earth, covered the sub, gave way to the Cenozoic Era (which is now).  

It's important to remember that each event happened because of the event that followed. For instance, the large insects that were the first terrestrial animals had followed plant onto land, implying that they had found a new food source in them. Also, the first bacteria to emerge were photosynthetic because the atmosphere had no breathable o2 at the time. The four eras discussed all have names that indicate their order. Precambrian means before wales, meaning it was before anything else. Then came the Palezioc, which means ancient animals, as this is where animals emerged. Then came the Mesozoic, with Mesozoic meaning middle and the cenzoic meaning new.

Madison Boggan
March 05, 2015 at 8:36pm

Parent: The whale meat sheet is conveying the idea that DNA sequencing can protect endangered species. Also, whales and hippos are closely related. This is a bummer because hippos are scary. 

Earth has 4 main eras which are precambrian, paleozoic, mesozoic and cenozoic. Bacteria first came to be in the precambrian as well as the first eukaryotes. Fish and land animals in the paleozoic, dino's in the mesozoic and we are now in the cenozoic (mammals). Madison and I talked about the connection between our family friends who eat a "paleo" diet and the meaning of the word and the era it refers to. Our friends eat a very basic, ancient diet as the word alludes to. 

Student: The connection to the paleozoic era and a paleo diet was interesting and will help me remember this era more. I am glad that my mom and I talked about this reconnect. Also, I explained to her that the different eras are like any other change that we see. If a pendulum swings to one side, it eventually swings back. When a change is made the pendulum swings one way then the swing back is the change or reaction to that. For example, during the precambrian era the first eukaryote's were introduced so in the next era, it makes sense that the swing back would be even more advanced and that would be fish, plants, animals and more. The era's make more sense when they are brought back to cause and effect. 

Amber Neathery
March 05, 2016 at 1:50pm

Student: The Earth is broken into 4 main eras: The precambrian era ("before Wales"), the paleozoic era ("old animals"), the mesozoic era (dinosaurs), and the cenozoic era (current). The oceans formed, cyanobacteria arose and sponge developed during the precambrian era. As a result of the cambrian explosion [of life], adaptive radiation gave rise to a larger diversity of life. Predation drives evolution in a sort of arms race. The first fish appear during the paleozoic era and the permian mass extinction served as the worst extinction in Earth's history, as 90% of life was destroyed as a result of climate change. The KT mass extinction at the end of the mesozoic era was the end of life for most dinosaurs, but the ones who survived evolved into birds, who dominated the beginning of the cenozoic era. Discussing this with my dad allowed me to talk about SS WEBBEG as we went through the impact that humans have had on the environment. 

Parent: four main eras are precambrian, paleozoic, mesozoic, cenozoic. predators cause evolution. amber drew a timeline that helped explain that humans have only been here a short amount of time. we talked about the damage that humans have done to the planet and amber explained that it is like the permian mass extinction.

Makaila Heifner
March 23, 2016 at 8:38pm

Parent: Makaila explained that there are 4 main eras in Earth's history: the precambrian, the paleozoic, mesozoic, and cenozoic. I thought it was really interesting that most of Earth's history did not have many animals or living organisms. I also found it interesting, but not surprising, how much damage humans have done to the planet. Something that struck me was the number of mass extinctions there has been, typically I only think about the mass extinction of the dinosaurs, but I didn't realize there was more than just one, and especially that humans are causing mass extinctions now. 

Student: We went over the various eras of Earth's history and the events that happened during them, such as when the oceans formed UV protections in the precambrian era nearly 4 billion years ago. We also talked a lot about the various mass extinctions and the rate at which humans are causing mass extinctions around the world. 

Zach Holtz
March 10, 2020 at 8:54pm

Student:   It was nice to review the earth's history.  The different periods consist of Precambrian, Paleozoic, Mesozoic, and Cenozoic.  Throughout all these time periods there have been new things that have formed.  These consist of the formation of the ocean, prokaryotes, atmosphere with O2, single-celled organisms, eukaryotes, Cambrian explosions, mass extinctions, animals, land colonization, and humans.

Parent:   I've learned this before, but forgot.  The earth formed 4.6 billion years ago...WOWSA!!!  Going over the 10 big events was interesting.  

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