Neohipparion affine (slender three-toed horses) in volcanic tuff (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, USA) 3 : 無料・フリー素材/写真
Neohipparion affine (slender three-toed horses) in volcanic tuff (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, 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 | Neohipparion affine (Leidy, 1869) - slender three-toed horse skeletons in volcanic tuff in the Miocene of Nebraska, USA.Volcanic tuff is a fine-grained, clastic-textured, extrusive igneous rock - basically a solidified volcanic ash deposit. Volcanic tuff can be well to poorly indurated / lithified. This exposure is at Nebraska's Ashfall Fossil Beds. The ash is derived from the Bruneau-Jarbidge Volcanic Field in southwestern Idaho's Snake River Plain. The wind-blown ash buried a vertebrate-rich biota at what was originally a Miocene waterhole.The fossils seen here are a jumble of two skeletons (adult and juvenile) of Neohipparion affine, the slender three-toed horse, a long-extinct species.------------------------------------------------From on-site info.:3-TOED MARE AND COLT SKELETONSThese skeletons have been disturbed (by trampling and scavening?). However, it is clear that the baby was between the adult's legs when it died.-------------Slender Three-toed HorseNeohipparionThe long, slender legs of this three-toed horse show that it was a fast runner. The large functional "side hooves" (one on each side of the main hoof) suggest that it was a good dodger as well and perhaps was better at dealing with soft, treacherous ground than the single-toed horses. Like the other four species of horses found in the ash bed, this one has tall-crowned molar teeth capable of grinding tough, silica-rich grss into digestible mush. The species found at Ashfall, Neohipparion affine, is larger than its ancestors found in older fossil beds and smaller than its descendants found in younger deposits.Single teeth of Neohipparion can be difficult to distinguish from those of Cormohipparion, hence the question marks about its occurrence above and beow the ash bed.Remains of this animal have been found:? In the "RECOVERY" layer (sandstone above the ash)X In the "DISASTER" layer (volcanic ash bed)? In the "WATERHOLE" layer (sandstone below the ash)Neohipparion was 4 feet (1.2 meters) at the shoulder.When the first fossils of three-toed horses were found in Europe, they were named Hipparion. When a skeleton of a similar horse was found later in South Dakota, it was named Neohipparion ('neo' means new) because of its occurrence in the New World.The Greek word for horse is "hippos" and "-arion" means "small" or "diminutive".------------------------------------------------Classification: Animalia, Chordata, Vertebrata, Mammalia, Perissodactyla, EquidaeStratigraphy: Cap Rock Member, Ash Hollow Formation, Ogallala Group, Miocene, 11.83 MaLocality: Hubbard Rhino Barn, Ashfall Fossil Beds State Historical Park, northeastern Nebraska, USA------------------------------------------------Info. at:en.wikipedia.org/wiki/Ashfall_Fossil_Beds |
| 撮影日 | 2011-08-05 13:29:48 |
| 撮影者 | James St. John |
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