Hystrivasum sp. (fossil snail shell) (Pliocene or Pleistocene; eastern USA) 1 : 無料・フリー素材/写真
Hystrivasum sp. (fossil snail shell) (Pliocene or Pleistocene; eastern USA) 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Hystrivasum sp. - fossil vase snail shell with borings from the upper Cenozoic of eastern America. (abapertural view)Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Most marine snails are herbivores (algae grazers) or predators/carnivores. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved.The numerous holes on the shell are borings - drillholes made by some invertebrate.Classification: Animalia, Mollusca, Gastropoda, Neogastropoda, TurbinellidaeStratigraphy: undetermined Pliocene or Pleistocene unitLocality: unrecorded |
| 撮影日 | 2018-12-12 15:02:43 |
| 撮影者 | James St. John |
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