Caririchnium leonardii (dinosaur tracks) (Dakota Sandstone, Lower Cretaceous; Dinosaur Ridge, Colorado, USA) 1 : 無料・フリー素材/写真
Caririchnium leonardii (dinosaur tracks) (Dakota Sandstone, Lower Cretaceous; Dinosaur Ridge, Colorado, 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 |
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| 説明 | Caririchnium leonardii Lockley, 1987 - iguanodontid dinosaur track in the Cretaceous of Colorado, USA.The outcrop shown above is part of Dinosaur Ridge (a section of the Dakota Hogback), which is a north-south trending ridge of eastward-dipping Mesozoic sedimentary rocks. Triassic, Jurassic, and Cretaceous rocks are present, tilted by Laramide Orogeny uplift during the Cenozoic (the Front Range of the Colorado Rocky Mountains is immediately west of here).This exposure consists of structurally tilted beds of the Dakota Sandstone, a Lower Cretaceous succession of nearshore terrestrial to intertidal to shallow marine quartz sandstone deposits. The eastern side of Dinosaur Ridge has a spectacular quartzose sandstone bedding plane with hundreds of dinosaur footprints. Researchers have identified 325 dinosaur footprint at this site, made by about 37 individual dinosaurs. The sediments probably represent a tidal flat that bordered the ancient Western Interior Seaway. The track makers were principally iguanodontid dinosaurs and a small theropod dinosaur. The tracks have been stained gray with charcoal to make them easier to see - the charcoal doesn't harm the tracks. Freeze-thaw weathering is destroying the tracks, and a building over this outcrop is planned.This dinosaur tracksite is next to a modern freeway - Interstate 470. As such, the dinosaur tracksite is often called the "Cretaceous 470" or "Dinosaur Freeway". This is part of a series of dinosaur tracksites that occur along the western edge of the Western Interior Seaway and the eastern edge of the Rocky Mountains. Together, they are called the Dinosaur Freeway Megatracksite.The fossil track shown above is the most common type of dinosaur footprints at this locality. This trace fossil has been given the scientific name Caririchnium leonardii. The large lower footprint is the pes (hindpaw) of an iguanodontid (ornithopod) dinosaur. The small upper footprint is the manus (front paw) of the same dinosaur. The manus was imprinted several moments before the pes. Dinosaur Ridge is the type locality for this particular dinosaur trace fossil.Stratigraphy: Dakota Sandstone, Albian Stage, upper Lower CretaceousLocality: eastern side of Dinosaur Ridge, between Interstate 70 and the town of Morrison, west of Denver, north-central Colorado, USA |
| 撮影日 | 2012-12-16 13:57:49 |
| 撮影者 | James St. John |
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