Partially silicified Hexagonaria (fossil coral) (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 3 : 無料・フリー素材/写真
Partially silicified Hexagonaria (fossil coral) (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 3 / 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 | Hexagonaria sp. - partially silicified fossil coral from the Devonian of Ohio, USA. (plan view)This fossil coral is from the Columbus Limestone, a significant carbonate unit in the Devonian of central and northern Ohio. It's actually part of a much more widespread sheet of Devonian carbonates that extends from New York State to the Midwest. The Columbus Limestone represents deposition in a subtropical, shallow-water, carbonate platform environment. The rocks are principally micritic limestones, fossiliferous wackestones, and fossiliferous packstones. Some chert nodules are present in the unit. Fossils are typical Paleozoic shallow marine invertebrates - favositid corals, rugose corals, stromatoporoids, brachiopods, crinoids, blastoids, bryozoans, trilobites, bivalves, gastropods, cephalopods, rostroconchs, and tentaculites. Microfossils include conodonts and charophyte oogonia. Other fossils in the Columbus Limestone include vertebrates (fish), land plants (rare), and trace fossils. Some horizons in the Columbus Limestone have silicified fossils.Corals are basically sea anemones (polyps) that make a skeleton, which is usually mineralized. Most corals are colonial, but some are solitary. This particular fossil coral is Hexagonaria, a colonial rugose coral having many hexagonally-shaped corallites (some are pentagonal), as seen in plan view (click on the photo to zoom in - look at the darker-colored areas). Each rounded depression within each hexagonal corallite was the seat for a polyp.The white-colored portions of this fossil are composed of quartz (SiO2); the darker-colored areas are calcareous (CaCO3). Fossils that have been preserved with a different mineral that the original hard parts are said to have been replaced. Quartz replacement in fossils is called silicification.Classification: Animalia, Cnidaria, Anthozoa, Rugosa, PhillipsastraeidaeStratigraphy: upper Columbus Limestone, Eifelian Stage, lower Middle DevonianLocality: loose piece from roadcut along the northern side of Emerald Parkway, immediately east of Rt. 257 intersection, Dublin, northwestern Franklin County, central Ohio, USA----------------------------------See info. at:en.wikipedia.org/wiki/Rugosa |
| 撮影日 | 2018-12-19 10:48:11 |
| 撮影者 | James St. John |
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