File:Radioactive dinosaur bone in sandstone (Morrison Formation, Upper Jurassic; western side of Dinosaur Ridge, Colorado, USA) (8277701353).jpg
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[edit]DescriptionRadioactive dinosaur bone in sandstone (Morrison Formation, Upper Jurassic; western side of Dinosaur Ridge, Colorado, USA) (8277701353).jpg |
Radioactive dinosaur bone (= dark structure in the rock) in sandstone in the Jurassic of Colorado, USA. Dinosaur Ridge is a particularly dinosaur fossil-rich section of the Dakota Hogback in north-central Colorado. It is a north-south trending ridge of eastward-dipping Mesozoic sedimentary rocks. The western side of Dinosaur Ridge (see above photo) has exposures of the Morrison Formation, an Upper Jurassic succession consisting of fluvial (river/floodplain) and lacustrine (lake) deposits, plus reddish-colored paleosol horizons. Dinosaur bones and dinosaur tracks have been found here. The fossil shown above is a large pubis bone from a sauropod dinosaur (probably Atlantosaurus) in a fluvial sandstone matrix. Several dinosaur bones occur at this site - part of a river channel sandstone deposit. Paleocurrent indicators show that the river system was flowing to the southeast. Sauropods were the largest and most massive group of dinosaurs - they had huge bodies, walked on four legs, and possessed very long tails and necks. Fossil bones of several different sauropod dinosaur species have been recovered from Dinosaur Ridge's Morrison Formation. Known Morrison sauropods in this area include (not counting junior synonyms) Atlantosaurus immanis, Apatosaurus ajax, and Camarasaurus sp. (see Mossbrucker & Bakker, 2010, pp. 10, 19, 22). Dinosaurologist Bob Bakker interprets the long pubis bones of sauropods as having a pubic mounting function. Pubic mounting is a type of behavior used to assert dominance over other animals. This sauropod pubic bone is radioactive. All of the dinosaur bones at this locality are radioactive. They have been partially permineralized/replaced by the radioactive, uranium-bearing mineral carnotite. A scintillometer reading on a dinosaur bone at this locality was 422 counts per minute (compared with a background reading of 140 cpm). Stratigraphy: Morrison Formation, Kimmeridgian Stage, middle Upper Jurassic, ~150 to 156 Ma Locality: "Quarry 5" (= one of Arthur Lakes' dinosaur excavation sites during the Cope-Marsh Bone Wars of the late 1800s), western side of Dinosaur Ridge, between Interstate 70 and the town of Morrison, west of Denver, north-central Colorado, USA Reference cited: Mossbrucker, M.T. & R.T. Bakker. 2010. A guide to the paleontology of the Upper Jurassic Morrison Formation of Morrison, Colorado: new interpretations and discoveries. Bulletin of the Morrison Natural History Museum 1. 35 pp. |
Date | |
Source | Radioactive dinosaur bone in sandstone (Morrison Formation, Upper Jurassic; western side of Dinosaur Ridge, Colorado, USA) |
Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/8277701353 (archive). It was reviewed on 6 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
6 December 2019
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current | 03:51, 6 December 2019 | 2,048 × 1,536 (972 KB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via #flickr2commons |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot S2 IS |
Exposure time | 1/80 sec (0.0125) |
F-number | f/2.7 |
Date and time of data generation | 20:07, 24 July 2009 |
Lens focal length | 6 mm |
Orientation | Normal |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
File change date and time | 20:07, 24 July 2009 |
Y and C positioning | Centered |
Exif version | 2.2 |
Date and time of digitizing | 20:07, 24 July 2009 |
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APEX aperture | 2.875 |
APEX exposure bias | 0 |
Maximum land aperture | 2.875 APEX (f/2.71) |
Metering mode | Pattern |
Flash | Flash did not fire, compulsory flash suppression |
Supported Flashpix version | 1 |
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File source | Digital still camera |
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