| 31. | They flourished particularly during the Carboniferous and Permian periods.
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| 32. | It preserves fossils dating to the Permian period.
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| 33. | They are known from the Middle Permian Period of what is now Russia and South Africa.
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| 34. | It has nearly vertical layers with continual exposure from the Permian period to the Cenozoic era.
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| 35. | The cave was developed in the Permian Period.
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| 36. | The tuff overlays shales and sandstones deposited during the Permian Period and limestone of Pennsylvanian age.
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| 37. | It lived during the early late Permian period.
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| 38. | The Mogollon Rim's limestones and sandstones were formed from sediments deposited in the Carboniferous and Permian Periods.
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| 39. | It lived in the Late Permian Period.
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| 40. | Between 270 and 255 million years ago, during the Permian period, the Appalachian Mountains began to form.
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