scholarly journals Paleomagnetism of the Late Triassic Petrified Forest Formation, Chinle Group, western United States: Further evidence of “large” rotation of the Colorado Plateau

2000 ◽  
Vol 105 (B11) ◽  
pp. 25791-25808 ◽  
Author(s):  
Maureen B. Steiner ◽  
Spencer G. Lucas
Keyword(s):  
United States ◽  
Colorado Plateau ◽  
Western United States ◽  
Late Triassic ◽  
Large Rotation ◽  
Chinle Group ◽  
Petrified Forest

scholarly journals Tetrapod extinctions during the Late Triassic: evidence from the western United States

1992 ◽  
Vol 6 ◽  
pp. 142-142
Author(s):  
Adrian P. Hunt ◽  
Spencer G. Lucas
Keyword(s):  
United States ◽  
Fossil Record ◽  
Western United States ◽  
Late Triassic ◽  
Great Area ◽  
Stratigraphic Record ◽  
Facies Change ◽  
Extensive Collection ◽  
Chinle Group ◽  
Early Late

Most recent workers have identified a major extinction of nonmarine tetrapods during the Late Triassic at the Carnian-Norian boundary. However, this identification is based principally on the stratigraphic distribution of tetrapods where there either is a major facies change at the Carnian-Norian boundary (Germany) or a significant unconformity that spans much of the early Norian (Argentina). Instead, we have examined the stratigraphic record of tetrapods in the western United States (Chinle Group) where there is a relatively continuous, nonmarine depositional and fossil record across the Carnian-Norian boundary that does not encompass major facies changes. The Chinle Group, because of its great area of exposure, more than one century of extensive collection and relatively complete publication, contains the world's best record of tetrapods across the Carnian-Norian boundary.The tetrapod record from the Chinle Group does not record a significant tetrapod extinction at the Carnian-Norian boundary. Instead, it documents a staggered extinction of some taxa during the late Carnian and the persistence of most taxa across the Carnian-Norian boundary. Thus, rhynchosaurs become extinct at the end of the early-late Carnian, whereas dicynodonts become extinct somewhat later, during the latest Carnian. Among metoposaurids, only the large taxa (Buettneria) disappear at the end of the Carnian. Other groups - phytosaurs, aetosaurs, rauisuchians, trilophosaurs, etc. - only exhibit some generic turnover at the Carnian-Norian boundary. The first appearance of dinosaurs, linked by some to a Carnian-Norian tetrapod extinction, is well in advance of the end of the Carnian. Thus, we conclude that the highest resolution tetrapod record of the late Carnian and early Norian does not document a significant tetrapod extinction at the end of the Carnian.

scholarly journals Distribution and Significance of Mesozoic Vertebrate Trace Fossils in Dinosaur National Monument

1992 ◽  
Vol 16 ◽  
pp. 74-85 ◽  
Author(s):  
Martin Lockley ◽  
Kelly Conrad ◽  
Marc Paquette ◽  
James Farlow
Keyword(s):  
United States ◽  
Lower Jurassic ◽  
Western United States ◽  
Late Triassic ◽  
North American Continent ◽  
National Monument ◽  
The North ◽  
Dinosaur National Monument ◽  
Chinle Group ◽  
Glen Canyon

Search for new tracksites has now revealed a total of 25 localities in the older Mesozoic sedimentary rocks of Dinosaur National Monument (DNM). To date, the most productive units have proved to be the Late Triassic Chinle Group and the mainly Early Jurassic Glen Canyon Group in the western part of DNM. In addition several sites, that are an integral part of the overall paleontological picture, have been found just outside the boundaries of DNM. All these sites (and stratigraphic levels) add up to a total of about 45 tracksites in the DNM area. Chinle sites have now yielded dozens of trackways of theropod dinosaurs, ?prosauropod dinosaurs, mammal-like reptiles, ?phytosaurs, aetosaurs, lepidosaurs and tanystropheids, producing one of the most diverse Late Triassic track assemblages known anywhere. The ?prosauropod tracks are the first Late Triassic examples ever reported from the North American continent. The Lower Jurassic has also yielded theropod and prosauropod dinosaur tracks. These tracks are useful for correlation with other Early Mesozoic tracksites around the world and can be used to help construct a series of track zones (or Palichnostratigraphy) for the western United States. The discovery of prosauropod tracks (Pseudotetrasauropus) in the Chinle Group and in the lower part of Glen Canyon Group (Otozoum) points to a much wider distribution of prosauropod tracks in the western United States than previously supposed, and the need for a thorough study of these and similar track types. Further examination of the Jurassic Cannel Formation close to the DNM boundaries, reveals several tracksites that require further study.

scholarly journals Sedimentology and Stratigraphy of the Morrison Formation in Dinosaur National Monument

1992 ◽  
Vol 16 ◽  
pp. 86-91
Author(s):  
Christine Turner ◽  
Fred Peterson
Keyword(s):  
United States ◽  
Colorado Plateau ◽  
Upper Jurassic ◽  
Western United States ◽  
Morrison Formation ◽  
National Monument ◽  
Dinosaur National Monument

The overall goal of this study is to establish a stratigraphic, sedimentologic, and geochronologic framework for the Upper Jurassic Morrison Formation within Dinosaur National Monument and to tie that framework to the rest of the Colorado Plateau and other important vertebrate fossil-bearing localities in the western United States. The study is also intended to complement ongoing paleontological inventories of the Morrison Formation within Dinosaur National Monument (DNM).

scholarly journals Colorado Plateau Coring Project, Phase I (CPCP-I): a continuously cored, globally exportable chronology of Triassic continental environmental change from western North America

2018 ◽  
Vol 24 ◽  
pp. 15-40 ◽  
Author(s):  
Paul E. Olsen ◽  
John W. Geissman ◽  
Dennis V. Kent ◽  
George E. Gehrels ◽  
Roland Mundil ◽  
...  
Keyword(s):  
North America ◽  
Environmental Change ◽  
National Park ◽  
Colorado Plateau ◽  
Global Environmental Change ◽  
Magnetic Polarity ◽  
Late Triassic ◽  
Western North America ◽  
Petrified Forest National Park ◽  
Petrified Forest

Abstract. Phase 1 of the Colorado Plateau Coring Project (CPCP-I) recovered a total of over 850 m of stratigraphically overlapping core from three coreholes at two sites in the Early to Middle and Late Triassic age largely fluvial Moenkopi and Chinle formations in Petrified Forest National Park (PFNP), northeastern Arizona, USA. Coring took place during November and December of 2013 and the project is now in its post-drilling science phase. The CPCP cores have abundant detrital zircon-producing layers (with survey LA-ICP-MS dates selectively resampled for CA-ID-TIMS U-Pb ages ranging in age from at least 210 to 241 Ma), which together with their magnetic polarity stratigraphy demonstrate that a globally exportable timescale can be produced from these continental sequences and in the process show that a prominent gap in the calibrated Phanerozoic record can be filled. The portion of core CPCP-PFNP13-1A for which the polarity stratigraphy has been completed thus far spans ∼215 to 209 Ma of the Late Triassic age, and strongly validates the longer Newark-Hartford Astrochronostratigraphic-calibrated magnetic Polarity Time-Scale (APTS) based on cores recovered in the 1990s during the Newark Basin Coring Project (NBCP). Core recovery was ∼100 % in all holes (Table 1). The coreholes were inclined ∼60–75∘ approximately to the south to ensure azimuthal orientation in the nearly flat-lying bedding, critical to the interpretation of paleomagentic polarity stratigraphy. The two longest of the cores (CPCP-PFNP13-1A and 2B) were CT-scanned in their entirety at the University of Texas High Resolution X-ray CT Facility in Austin, TX, and subsequently along with 2A, all cores were split and processed at the CSDCO/LacCore Facility, in Minneapolis, MN, where they were scanned for physical property logs and imaging. While remaining the property of the Federal Government, the archive half of each core is curated at the NSF-sponsored LacCore Core Repository and the working half is stored at the Rutgers University Core Repository in Piscataway, NJ, where the initial sampling party was held in 2015 with several additional sampling events following. Additional planned study will recover the rest of the polarity stratigraphy of the cores as additional zircon ages, sedimentary structure and paleosol facies analysis, stable isotope geochemistry, and calibrated XRF core scanning are accomplished. Together with strategic outcrop studies in Petrified Forest National Park and environs, these cores will allow the vast amount of surface paleontological and paleoenvironmental information recorded in the continental Triassic of western North America to be confidently placed in a secure context along with important events such as the giant Manicouagan impact at ∼215.5 Ma (Ramezani et al., 2005) and long wavelength astronomical cycles pacing global environmental change and trends in atmospheric gas composition during the dawn of the dinosaurs.

Late Triassic dinosaursfrom the western United States

Geobios ◽  
1998 ◽  
Vol 31 (4) ◽  
pp. 511-531 ◽  
Author(s):  
Adrian P. Hunt ◽  
Spencer G. Lucas ◽  
Andrew B. Heckert ◽  
Robert M. Sullivan ◽  
Martin G. Lockley
Keyword(s):  
United States ◽  
Western United States ◽  
Late Triassic
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