Pudoproetus auriculatus fossil trilobite (Byer Sandstone, Lower Mississippian; Rt. 16 roadcut, 1.45 miles south of Granville, Ohio, USA) 2 : 無料・フリー素材/写真
Pudoproetus auriculatus fossil trilobite (Byer Sandstone, Lower Mississippian; Rt. 16 roadcut, 1.45 miles south of Granville, Ohio, 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 | Pudoproetus auriculatus fossil trilobite from the Mississippian of Ohio, USA. (specimen collected 1961 by William D. Nichols; housed at the Orton Geology Museum, Ohio State University, Columbus, Ohio, USA) (centimeter scale)Trilobites are extinct marine arthropods. They first appear in Lower Cambrian rocks and the entire group went extinct at the end of the Permian. Trilobites had a calcitic exoskeleton and nonmineralizing parts underneath (legs, gills, gut, etc.). The calcite skeleton is most commonly preserved in the fossil record, although soft-part preservation is known in some trilobites (Ex: Burgess Shale and Hunsruck Slate). Trilobites had a head (cephalon), a body of many segments (thorax), and a tail (pygidium). Molts and carcasses usually fell apart quickly - most trilobite fossils are isolated parts of the head (cranidium and free cheeks), individual thoracic segments, or isolated pygidia. The name "trilobite" was introduced in 1771 by Johann Ernst Immanuel Walch and refers to the tripartite division of the trilobite body - it has a central axial lobe that runs longitudinally from the head to the tail, plus two side lobes (pleural lobes).Well preserved specimens of the proetide trilobite Pudoproetus auriculatus (also known as Pudoproetus missouriensis) are rare. The specimen shown above is an internal mold of a complete exoskeleton in fossiliferous quartzose sandstone. These fossils have an orangish-brown coating of limonite (FeO·OH·nH2O - hydrous iron hydroxy-oxide). The trilobite is closely associated with isolated crinoid stem columnals. Classification: Animalia, Arthropoda, Trilobite, Polymerida, Proetida, ProetidaeStratigraphy: Byer Sandstone Member, lower Logan Formation, lower Osagean Stage, upper Lower Mississippian. Locality: roadcut on western side of Rt. 16, ~1.45 miles south of Granville, central Licking County, central Ohio, USA. |
| 撮影日 | 2014-09-17 00:14:59 |
| 撮影者 | James St. John |
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