Fossilization of Bat Skeletons in the Carlsbad Caverns


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Bulletin of the National Speleological Society

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—Cave deposits are important sites for the large accumulation and preservation of animal remains. Most of what we know about fossil bats is derived from cavern sediments. Bats estimated to number in the trillions have lived within the Carlsbad Caverns over a period of at least 17,000 years. Vast deposits of their guano and skeletal remains are found throughout the Caverns. In those rooms which are now, or have been inhabited, both guano and bone material is found. In other rooms, skeletal remains only are found. These latter rooms are not inhabited intentionally, but, having small entrances through which bats might enter accidentally on a random flight, they act as natural traps. Becoming lost and trapped, the bats die within these rooms and their bones accumulate in the pits and depressions in the floors. Fossilization of some of the bones occurs beneath silt and calcite which covers them. Some bats are preserved in toto within the tops of active formations (speleothems) by the rapid deposition of calcite. Most skeletons, however, are disarticulated. A few bones become the nuclei for the forming of cave pearls. The large deposits of bat skeletons in the Carlsbad Caverns are probably the most extensive of any found in the large bat caves of the Southwest.

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