Fish began colonizing land during the Silurian period to escape competition in the oceans and find new food sources on land. They evolved legs to help navigate shallow waters, and these legs eventually allowed them to move permanently onto land. As they adapted to life on land, fish developed internal gas exchange systems and stronger limbs. Scientists study the fossil record to understand how organisms evolved over time. Neil Shubin of the University of Chicago has discovered many fossils showing the transition of fish to land-dwelling tetrapods, including a "missing link" creature from 375 million years ago that had features of both fish and crocodiles. By the Devonian period, tetrapods with four limbs had become the dominant land animals.

1. Evolving To Come On Land By: Rohan Parikh

2. Coming On To Land Silurian period (440 - 410 million years ago). Fish came to landto escape competition in the marine ecosystem. An opportunity to escape predators and the availability of new terrestrial niches. Fish originally evolved to have legs to help them in shallow water, then eventually the legs became longer and the fish moved on to land permanently, than they colonized on land. When fish moved onto land they had many problems, so they had to evolve around them like creating internal gas exchange systems, strong support systems so they could move about the land.

3. How Do We Know What We Know We know all of our information because of the fossil record, the fossil record tells us what the organism looked like and gives us a rough estimate on how long ago it existed, then we can put all the pieces together and see what evolved from what organism. That's how we know land animals evolved from fish. Scientists found a creature that looked like a cross between a fish and a crocodile that existed between 375 million years ago in Canada. The scientists concluded it evolved from fish and had four legs and swam in shallow water and could go on land. The animal was in the middle of evolving into a crocodile.

4. The Scientist Involved With Evolution of Fish Coming on Land Neil H. Shubin of the University of Chicago Shubin is involved with digging up fossils and placing them in the fossil record. Then he goes through the fossil record and compares the fossil he finds to other fossils to find any similarities. He mainly does his work in the Canadian Arctic. In 2006, Shubin found a large scaly creature that had never been seen before. He said itis the "missing link" in the evolution of some fishes from the water, to a life on walking on four limbs on land.

5. Tetrapods By the Devonian period one major animal group dominated the land, the tetrapods (4-legged terrestrial vertebrates). The first tetrapods were amphibians. These early amphibians were large-bodied animals with strong bodies and prominent ribs, and had legs. It was originally believed that the tetrapods evolved during periods of drought, when the ability to move between pools would be an advantage.

6. Other Theories Some people had the idea that animals originally started on land and then moved into the water, However, their theories have been proven wrong in many ways, but those people still think life started on land.Those people look at the fossil record backwards, feet evolved into fins.

7. Graphics Evolution in Fishes Evolution in Whales

8. Evolutionary Significance Evolutionists believe that tetrapods, vertebrates with four limbs, were the first animals to move on to the land, having evolved from a fish ancestor during the Devonian period (408 to 360 million years ago). The fossil record of Devonian tetrapods is often presented as compelling evidence of this major evolutionary transition.

9. Bibliography Morelle, Rebecca. "Arctic fossils mark move to land." BBC News. N.p., 4/5/06. Web. 21 Mar 2011.<http://news.bbc.co.uk/2/hi/science/nature/479672.stm>. "Plant and Animal Evolution." Evolution for Teaching. N.p., n.d. Web. 21 Mar 2011. <http://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml>. F, Spoor. "Transitional Forms of Whales ." Darwainia and Evolution. N.p., n.d. Web. 21 Mar 2011. <http://darwiniana.org/landtosea.htm>. Garner, Paul. "The fossil record of ‘early’ tetrapods: evidence of a major evolutionary transition? ." N.p., Augest 2003. Web. 21 Mar 2011. <http://www.answersingenesis.org/tj/v17/i2/tetrapod.asp>.