Kirkidium laqueatum pentamerid brachiopods in limestone (bioherm facies of the Wabash Formation, Ludlovian Series, Upper Silurian; Pipe Creek Junior Quarry, Swayzee, Indiana, USA) 2 : 無料・フリー素材/写真
Kirkidium laqueatum pentamerid brachiopods in limestone (bioherm facies of the Wabash Formation, Ludlovian Series, Upper Silurian; Pipe Creek Junior Quarry, Swayzee, Indiana, USA) 2 / 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 | Kirkidium laqueatum (or Kirkidium cf. K. laqueatum) pentamerid brachiopods in limestone from the Silurian of Indiana, USA.Brachiopods are sessile, benthic, filter-feeding, marine invertebrates. They first appear in Cambrian rocks and were abundant in Earth's oceans throughout the Paleozoic. They were also common in Mesozoic oceans, but are scarce in modern oceanic biotas. Brachiopods have two shells, called valves, that are usually calcareous (made of calcite - CaCO3 - calcium carbonate). Each shell of a brachiopod is bilaterally symmetrical, unlike each shell of a bivalve (clam).Pentamerids are usually large brachiopods that are moderately common in Silurian dolostones of America's Midwest. The calcite shell has usually dissolved away, leaving an internal mold. The pentamerid specimens shown above have preserved calcite shells because the host rocks have not been dolomitized.Classification: Animalia, Brachiopoda, Articulata (a.k.a. Rhynchonelliformea), Pentamerida, PentameridaeStratigraphy: bioherm facies of the Wabash Formation, Ludlovian Series, Upper SilurianLocality: upper part of the Pipe Creek Junior Quarry, Swayzee, east-central Indiana, USA |
| 撮影日 | 2015-04-12 09:55:23 |
| 撮影者 | James St. John |
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