Invasion_of_Land[1]

Invasion_of_Land[1] - Evolution of Land by Vertebrates...

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Evolution of Land by Vertebrates
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Invasion of Land by Vertebrates Tetrapods appeared during the Devonian period Plants and arthopods had already established terrestrial communities, and the climate was relatively mild. Arthropods and other invertebrates colonized land over 100 MY before. Thus, there was food to eat!
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Problems for invading vertebrates Desiccation It is wet in the water, and dry on land So water is lost through skin and respiratory surfaces, and from eggs Support Air is not as dense as water, so it does not provide support Not only is support required, but means for active locomotion on land is also required Sensation Air doesn’t transmit sound as well as water, but vision might work better over longer distances Temperature Air warms up and cools down much faster than water. Low temperature on land can inhibit activity.
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Advantages to invasion of land New food resources Avoidance of aquatic predators and competitors Oxygen abundant
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Phylogeny of Earliest Land Vertebrates Lungfish are most closely related among living animals to tetrapods . The closest relatives of the early tetrapods already had: - lungs - lobe fins (which could push against things) -and may have had pulmonary circulation
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Phylogeny of Earliest Land Vertebrates The early ancestors of terrestrial vertebrates diversified, with increasingly terrestrial forms appearing in the late Devonian and into the Carboniferous They were once thought to be adapted to survive the drying of ponds. Now most believe they used their limbs first in water.
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Lobe-fin relatives of tetrapods lived in shallow, swampy environments, and may have led lives similar to crocodiles, when they were in the water Lobe fins may have been useful in pushing the fish over submerged rocks, roots, etc.
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This note was uploaded on 09/23/2011 for the course BIOL 240 taught by Professor Staff during the Spring '11 term at S.F. State.

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Invasion_of_Land[1] - Evolution of Land by Vertebrates...

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