The - the amphibians. Animals (both vertebrate as well as...

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The "Tetrapods" The term "tetrapod" (meaning four-limbed or four-footed) has historically been applied to the land vertebrates (amphibians, reptiles, dinosaurs, birds, and mammals). There have recently been proposals to restrict its use to a more cladistically sound definition, summarized by The Definition of the Taxon Tetrapoda . All other animals from this point have four limbs and are called tetrapods. I use the term here not in the strict cladistic sense, but in a more inclusive sense to include the living forms as well as fossil vertebrates that had free digits. A discussion of tetrapod phylogeny is available at Phylogeny of stegocephalians , from the Tree of Life Page . Most zoologists would accept that the Devonian lobe-finned fishes were ancestral to
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Unformatted text preview: the amphibians. Animals (both vertebrate as well as many invertebrates such as insects) that live on land use limbs to support the body, especially since air is less buoyant than water. Lobe-finned fishes and early amphibians also had lungs and internal nares to respire air. Two hypotheses have been proposed to explain the evolution of amphibians from lobe-finned fishes. 1. Lobe-finned fishes capable of moving from pond-to-pond had an advantage over those that could not. 2. The supply of food on land, and the absence of predators, promoted adaptation to land. The first amphibians diversified during Carboniferous Period (commonly known as the Age of Amphibians)....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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