In our diagram, the first version of Sid is only made for water. There is no way for it to go on land. All the animals were in the oceans which made predators' lives very easy. But the smaller animals, the prey, were always in danger.
The first animals went on land during the Silurian Period; they were arthropods, such as spiders, centipedes, and mites. Because there were no predators, these arthropods did very well. Some even grew up to six feet long. Thriving on land, the arthropods had an awesome life until the sea scorpion went on land. Sadly for the arthropods, they were not fast enough to escape their new predator on land. Sid was never an arthropod, so this is not represented in our diagram.
45 million years after the arthropods, during the Devonian Period, amphibians came out of the ocean. It started out as air-breathing fish with small, weak legs that allowed them to go short distances on land. They could switch bodies of water, such as from one lake to another. They were the ancestors of amphibians. As amphibians developed, they became larger, with outlined feet and limbs, as well as strong rib cages. These amphibians lead to reptiles.
The reptiles took the place of amphibians during the Carboniferous period. With feet more like claws, tougher skin, and hard-shelled eggs, they were much more prepared for life out of water.
References
Erickson, J. Fossils of terrestrial organisms. In Science online. Retrieved from http://www.fofweb.com/activelink2.aspItemID=WE40&SID=5&iPin=AIFM0006&SingleRecord=True
Evolution: Change: Deep Time. (n.d.). Retrieved September 21, 2014, from PBS website: http://www.pbs.org/wgbh/evolution/change/deeptime/
Lund University. (2014, September 2). Spinach extract decreases cravings, aids weight loss. ScienceDaily. Retrieved September 8, 2014 from www.sciencedaily.com/releases/2014/09/140902114928.htm
Erickson, J. Fossils of terrestrial organisms. In Science online. Retrieved from http://www.fofweb.com/activelink2.aspItemID=WE40&SID=5&iPin=AIFM0006&SingleRecord=True
Evolution: Change: Deep Time. (n.d.). Retrieved September 21, 2014, from PBS website: http://www.pbs.org/wgbh/evolution/change/deeptime/
Lund University. (2014, September 2). Spinach extract decreases cravings, aids weight loss. ScienceDaily. Retrieved September 8, 2014 from www.sciencedaily.com/releases/2014/09/140902114928.htm
This is really cool that long ago animals moved from water to land. Awesome that some insects grew up to 6 feet long. Crazy!
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