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Unlike amphibians and reptiles, all mammals have ____.
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amphibians
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Most reptiles are thick-skinned and are covered with ____.
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birds
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All ____ living today are dinosaurs.
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dinosaurs
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Reptiles evolved from amphibians, which evolved from ____.
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eggs
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Non-avian ____ roamed the Earth for about 165 million years.
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fish
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Most female birds, reptiles, amphibians, and fish lay ____.
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hair
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Frogs, newts, salamanders, and toads are classified as ____.
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reptiles
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Alligators, lizards, snakes, and turtles are classified as ____.
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scales
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