Fossil shark tooth (Sanders Group, Mississippian; Henderson Creek roadcut, Lawrence County, Indiana, USA) 1 : 無料・フリー素材/写真
Fossil shark tooth (Sanders Group, Mississippian; Henderson Creek roadcut, Lawrence County, Indiana, 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 |
|---|---|
| 説明 | Fossil shark tooth from the Mississippian of Indiana, USA.The oldest known fish bones are fragments from the Upper Cambrian. Soft-bodied chordates referred to as “vertebrates” or “fish” are known from the Lower Cambrian and Middle Cambrian. The earliest, decent fossils of true fish are in the Ordovician. These remains show that the first fish lacked jaws. The evolution of jaws involved morphologic modification of the anterior pairs of gill arches. By the Devonian, jawed fishes had diversified into many distinct groups and became an important component of ancient oceans. The Devonian is often nicknamed “The Age of Fishes”.Seen here is the occlusal surface of a shell-crushing tooth from a fossil shark - probably Helodus.Classification: Animalia, Chordata, Vertebrata, Chondrichthyes, Euchondrocephali, HelodontidaeStratigraphy: float from the Ramp Creek Formation (middle Sanders Group, upper Osagean Stage, lower Malmeyeran Series, upper Lower Mississippian) or the Harrodsburg Limestone (middle Sanders Group, upper Osagean Stage to lower Meramecian Stage, middle Valmeyeran Series, upper Lower Mississippian to lower Middle Mississippian)Locality: talus from the base of a roadcut along Rt. 446, just south of Henderson Creek, due west of Norman Station, just east of due north of Heltonville (NE1/4 of section 14, T6N, R1E, Norman Quadrangle), central Pleasant Run Township, northeastern Lawrence County, south-central Indiana, USA |
| 撮影日 | 2017-05-26 14:23:09 |
| 撮影者 | James St. John |
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