scholarly journals The Morrison Formation Extinct Ecosystems Project

1996 ◽  
Vol 20 ◽  
pp. 20-27
Author(s):  
Christine Turner ◽  
Fred Peterson ◽  
D. Chure ◽  
T. Demko ◽  
G. Engelmann
Keyword(s):  
United States ◽  
Late Jurassic ◽  
The United States ◽  
Upper Jurassic ◽  
Morrison Formation

The Morrison Project is a multidisciplinary effort to interpret the ancient ecosystem that was present in the Western Interior of the United States during deposition of the Upper Jurassic Morrison Formation. The project began in June of 1994 and the first two years of research (1994-95, 1995-96) were devoted primarily to identifying problems and gathering information that would form the basis for later interpretations. Efforts during the final year (1996-97) were directed toward resolving remaining problems or conflicting findings and synthesizing the various research endeavors into a reconstruction of the Late Jurassic ecosystem.

scholarly journals Detrital zircon geochronology and provenance of the Middle to Late Jurassic Paradox Basin and Central Colorado trough: Paleogeographic implications for southwestern Laurentia

Geosphere ◽  
2021 ◽  
Author(s):  
John I. Ejembi ◽  
Sally L. Potter-McIntyre ◽  
Glenn R. Sharman ◽  
Tyson M. Smith ◽  
Joel E. Saylor ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Detrital Zircon ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Morrison Formation ◽  
Detrital Zircon Geochronology ◽  
Sediment Dispersal ◽  
Paradox Basin ◽  
Southern Oklahoma ◽  
Trace Elemental

Middle to Upper Jurassic strata in the Paradox Basin and Central Colorado trough (CCT; south­western United States) record a pronounced change in sediment dispersal from dominantly aeolian deposition with an Appalachian source (Entrada Sandstone) to dominantly fluvial deposi­tion with a source in the Mogollon and/or Sevier orogenic highlands (Salt Wash Member of the Morrison Formation). An enigmatic abundance of Cambrian (ca. 527–519 Ma) grains at this prove­nance transition in the CCT at Escalante Canyon, Colorado, was recently suggested to reflect a local sediment source from the Ancestral Front Range, despite previous interpretations that local base­ment uplifts were largely buried by Middle to Late Jurassic time. This study aims to delineate spatial and tem­poral patterns in provenance of these Jurassic sandstones containing Cambrian grains within the Paradox Basin and CCT using sandstone petrog­raphy, detrital zircon U-Pb geochronology, and detrital zircon trace elemental and rare-earth ele­mental (REE) geochemistry. We report 7887 new U-Pb detrital zircon analyses from 31 sandstone samples collected within seven transects in west­ern Colorado and eastern Utah. Three clusters of zircon ages are consistently present (1.53–1.3 Ga, 1.3–0.9 Ga, and 500–300 Ma) that are interpreted to reflect sources associated with the Appalachian orogen in southeastern Laurentia (mid-continent, Grenville, Appalachian, and peri-Gondwanan terranes). Ca. 540–500 Ma zircon grains are anom­alously abundant locally in the uppermost Entrada Sandstone and Wanakah Formation but are either lacking or present in small fractions in the overlying Salt Wash and Tidwell Members of the Morrison Formation. A comparison of zircon REE geochem­istry between Cambrian detrital zircon and igneous zircon from potential sources shows that these 540–500 Ma detrital zircon are primarily magmatic. Although variability in both detrital and igneous REE concentrations precludes definitive identifica­tion of provenance, several considerations suggest that distal sources from the Cambrian granitic and rhyolitic provinces of the Southern Oklahoma aulacogen is also likely, in addition to a proximal source identified in the McClure Mountain syenite of the Wet Mountains, Colorado. The abundance of Cambrian grains in samples from the central CCT, particularly in the Entrada Sandstone and Wana­kah Formation, suggests northwesterly sediment transport within the CCT, with sediment sourced from Ancestral Rocky Mountains uplifts of the southern Wet Mountains and/or Amarillo-Wichita Mountains in southwestern Oklahoma. The lack of Cambrian grains within the Paradox Basin sug­gests that the Uncompahgre uplift (southwestern Colorado) acted as a barrier to sediment transport from the CCT.

scholarly journals Decomposition of dinosaurian remains inferred by invertebrate traces on vertebrate bone reveal new insights into Late Jurassic ecology, decay, and climate in western Colorado

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9510
Author(s):  
Julia B. McHugh ◽  
Stephanie K. Drumheller ◽  
Anja Riedel ◽  
Miriam Kane
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Site Formation ◽  
Morrison Formation ◽  
Bone Surface ◽  
The North ◽  
Western Colorado ◽  
Burial Rates ◽  
Minimum Residence Time ◽  
Taphonomic Analysis

A survey of 2,368 vertebrate fossils from the Upper Jurassic Mygatt-Moore Quarry (MMQ) (Morrison Formation, Brushy Basin Member) in western Colorado revealed 2,161 bone surface modifications on 884 specimens. This is the largest, site-wide bone surface modification survey of any Jurassic locality. Traces made by invertebrate actors were common in the assemblage, second in observed frequency after vertebrate bite marks. Invertebrate traces are found on 16.174% of the total surveyed material and comprise 20.148% of all identified traces. Six distinct invertebrate trace types were identified, including pits and furrows, rosettes, two types of bioglyph scrapes, bore holes and chambers. A minimum of four trace makers are indicated by the types, sizes and morphologies of the traces. Potential trace makers are inferred to be dermestid or clerid beetles, gastropods, an unknown necrophagous insect, and an unknown osteophagus insect. Of these, only gastropods are preserved at the site as body fossils. The remaining potential trace makers are part of the hidden paleodiversity from the North American Late Jurassic Period, revealed only through this ichnologic and taphonomic analysis. Site taphonomy suggests variable, but generally slow burial rates that range from months up to 6 years, while invertebrate traces on exposed elements indicate a minimum residence time of five months for carcasses with even few preserved invertebrate traces. These traces provide insight into the paleoecology, paleoclimate, and site formation of the MMQ, especially with regards to residence times of the skeletal remains on the paleolandscape. Comprehensive taphonomic studies, like this survey, are useful in exploring patterns of paleoecology and site formation, but they are also rare in Mesozoic assemblages. Additional work is required to determine if 16.174% is typical of bulk-collected fossils from Jurassic ecosystems in North America, or if the MMQ represents an unusual locality.

The systematic position of the Late Jurassic alleged dinosaur Macelognathus (Crocodylomorpha: Sphenosuchia)

2005 ◽  
Vol 42 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Ursula B Göhlich ◽  
Luis M Chiappe ◽  
James M Clark ◽  
Hans-Dieter Sues
Keyword(s):  
Late Jurassic ◽  
Upper Jurassic ◽  
Systematic Position ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Morrison Formation ◽  
Postcranial Skeleton ◽  
Western Colorado ◽  
New Material ◽  
Limb Posture

Macelognathus vagans was described by O.C. Marsh in 1884, based on a mandibular symphysis from the Upper Jurassic Morrison Formation of Wyoming. Often considered a dinosaur but later tentatively referred to the Crocodylia, its phylogenetic identity has until now been enigmatic. New material of this species from the Morrison Formation of western Colorado demonstrates its affinities with basal crocodylomorphs commonly grouped together as the Sphenosuchia, which are characterized by a gracile postcranial skeleton with erect limb posture. Macelognathus shares features with Kayentasuchus from the Lower Jurassic Kayenta Formation of Arizona and Hallopus, which may be from the Morrison Formation of eastern Colorado. The new material constitutes the youngest definitive occurrence of a sphenosuchian, previously known from the Late Triassic to the Middle or Late? Jurassic.

scholarly journals The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines

2013 ◽  
Author(s):  
Michael P Taylor ◽  
Mathew J Wedel
Keyword(s):  
United States ◽  
Cervical Vertebrae ◽  
Ground Level ◽  
Upper Jurassic ◽  
Western United States ◽  
Morrison Formation ◽  
Feeding Style ◽  
Functional Complex ◽  
Characteristic Features

Barosaurus is a diplodocid sauropod from the Upper Jurassic Morrison Formation of the western United States, and is known for its very long neck. It is related to the sympatric Diplodocus, and often thought of as more or less identical except with a longer neck. The holotype YPM 429 includes three and a half posterior cervical vertebrae, somewhat distorted and damaged, which are nevertheless very distinctive and quite different from those of Diplodocus. The cervicals of the better known and more complete referred Barosaurus specimen AMNH 6341 show the same characteristic features as the holotype, though not to the same extent: transversely broad but anteroposteriorly short zygapophyseal facets; prezygapophyses carried on broad, squared-off rami; zygapophyses shifted forward relative to the centrum; diapophyses, parapophyses and neural spines shifted backwards; and broad diapophyseal “wings”. These features form a single functional complex, enabling great lateral flexibility, but restricting vertical flexibility. This may indicate that Barosaurus used a different feeding style from other sauropods perhaps sweeping out long arcs at ground level. The Morrison Formation contains at least nine diplodocid species in six to eight genera whose relationships are not yet fully understood, but Barosaurus remains distinct from its relatives.

scholarly journals Morrison Ecosystem Project

1994 ◽  
Vol 18 ◽  
pp. 152-155
Author(s):  
Christine Turner ◽  
Fred Peterson
Keyword(s):  
National Park ◽  
Late Jurassic ◽  
Rocky Mountain ◽  
The United States ◽  
Morrison Formation ◽  
National Monument ◽  
Management Actions ◽  
Rocky Mountain Region ◽  
Park Service ◽  
Recreation Area

The Late Jurassic Morrison Formation is one of science's best windows into the world of dinosaurs and Mesozoic ecosystems. The Morrison Formation has significant exposures in many units within the Rocky Mountain Region of the National Park Service. These include Arches National Park (ARCH), Bighorn National Recreation Area (BIRO), Black Canyon of the Gunnison National Monument (BLCA), Capitol Reef National Park (CARE), Colorado National Monument (COLO), Curecanti National Recreation Area (CURE), Dinosaur National Monument (DINO), Glacier National Park (GLAC), Glen Canyon National Recreation Area (GLCA), Hovenweep National Monument (HOVE), and Yellowstone National Park (YELL). The Morrison Formation Extinct Ecosystems Project, hereafter called the Morrison Project, began on June 1 of 1994. The project is a multidisciplinary endeavor to determine the nature, distribution, and evolution of the ancient ecosystems that existed in the Western Interior of the United States during the Late Jurassic Epoch when the Morrison Formation and related rocks were deposited. The information obtained from the research can be used to suggest appropriate resource management actions and the project will also provide an improved understanding of the geological and paleontological history of these NPS units and better information for interpretive programs and publications.

scholarly journals An unusually diverse northern biota from the Morrison Formation (Upper Jurassic), Black Hills, Wyoming

2020 ◽  
Vol 7 ◽  
pp. 29-67
Author(s):  
John Foster ◽  
Darrin Pagnac ◽  
ReBecca Hunt-Foster
Keyword(s):  
North America ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
River Channel ◽  
Black Hills ◽  
Morrison Formation ◽  
Vertebrate Fauna ◽  
Type Area ◽  
First Occurrence

The Little Houston Quarry in the Black Hills of Wyoming contains the most diverse vertebrate fauna in the Morrison Formation (Upper Jurassic) north of Como Bluff and the second-most diverse in the entire formation, after Reed’s Quarry 9. The deposit was an occasionally reactivated abandoned river channel, in interbedded green mudstone and laminated green-gray siltstone above a channel sandstone. The dinosaur material is densely distributed and is disarticulated to articulated, with several associated skeletons. The biota contains charophytes, horsetails, a possible seed fern, possible conifers, gastropods, two types of unionoid bivalves, diplostracans (“conchostracans”), a malacostracan, ray-finned fish, lungfish, a frog, salamanders, two types of turtles, rhynchocephalians, a lizard, choristoderes, two types of crocodyliforms, a pterosaur, Allosaurus and several types of small theropods including Tanycolagreus? and probable dromaeosaurids, numerous Camarasaurus and a diplodocine sauropod, a stegosaur, the neornithischian Nanosaurus, and the mammals Docodon, Amblotherium, and a multituberculate. Among these taxa, one of the unionoid bivalves, an atoposaurid crocodyliform, and the species of Amblotherium, which appear to be new and unique to the locality so far. The Docodon material may represent the first occurrence of D. apoxys outside of its type area in Colorado. Additionally, small, unusual theropod tooth types reported here may represent the first Late Jurassic occurrence of cf. Richardoestesia in North America and a possible abelisauroid, respectively.

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 The neck of Barosaurus: longer, wider and weirder than those of Diplodocus and other diplodocines

2016 ◽  
Author(s):  
Michael P Taylor ◽  
Mathew J Wedel
Keyword(s):  
United States ◽  
Cervical Vertebrae ◽  
Ground Level ◽  
Upper Jurassic ◽  
Western United States ◽  
Morrison Formation ◽  
Feeding Style ◽  
Functional Complex ◽  
Characteristic Features

Barosaurus is a diplodocid sauropod from the Upper Jurassic Morrison Formation of the western United States, and is known for its very long neck. It is closely related to the sympatric Diplodocus, and often thought of as more or less identical except with a longer neck. The holotype YPM 429 includes three and a half posterior cervical vertebrae, somewhat distorted and damaged, which are nevertheless very distinctive and quite different from those of Diplodocus. The cervicals of the better known and more complete referred Barosaurus specimen AMNH 6341 show the same characteristic features as the holotype, though not to the same extent: transversely broad but anteroposteriorly short zygapophyseal facets; prezygapophyses carried on broad, squared-off rami; zygapophyses shifted forward relative to the centrum; diapophyses, parapophyses and neural spines shifted backwards; and broad diapophyseal “wings”. These features form a single functional complex, enabling great lateral flexibility, but restricting vertical flexibility. This may indicate that Barosaurus used a different feeding style from other sauropods perhaps sweeping out long arcs at ground level. The Morrison Formation contains at least nine diplodocid species in six to eight genera whose relationships are not yet fully understood, but Barosaurus remains distinct from its relatives.

scholarly journals Deep oil. Offshore deposits of the Gulf of Mexico

2021 ◽  
Vol 3 (1) ◽  
pp. 3-21
Author(s):  
K. O. Iskaziev ◽  
P. E. Syngaevsky ◽  
S. F. Khafizov
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Oil And Gas ◽  
New Technologies ◽  
The United States ◽  
Upper Jurassic ◽  
Seismic Facies ◽  
Oil Companies ◽  
History Of ◽  
Hydrocarbon Deposits

This article continues a series of reviews of the worlds oil and gas basins, where active exploration and development of hydrocarbon deposits in superdeep (6 km +) horizons are taking place, as probable analogues of projects in the Caspian megabasin, primarily the Eurasia project. In this regard the Gulf of Mexico is of great interest, since this region is very well studies over such a long history of its development and thus makes it possible to analyze a huge amount of data collected during this time. The Gulf of Mexico includes the deep-water, offshore and coastal parts of three countries the United States, Mexico and Cuba, and is one of the most important oil and gas provinces in the world. Its deposits are represented by various complexes from the Middle Jurassic to modern sediments, with a total thickness of 14,000 m and more. Exploration for hydrocarbons has been going on here for almost 100 years. During this time, various new technologies have been developed and successfully applied, such as forecasting abnormally high reservoir pressure, cyclostratigraphy and seismic facies analysis, characterization of low-resistivity productive reservoirs and the search for ultra-deep hydrocarbon deposits. Of all the variety of objects developed in the Gulf, in the context of the study of deep deposits, the main interest and possible associations with the Caspian megabasin are the deposits of the Norflet Formation of the Upper Jurassic, which are discussed in the main part of this article. Of course, we are not talking about a direct comparison; in particular, the aeolian origin of part of the section makes this object significantly different. Nevertheless, according to the authors, studying it, as well as understanding how a successful project for its development is being implemented right before our eyes, can provide a lot of important information for working in the deep horizons of the Caspian region. The article is divided into two parts. The first examines the geological history of the formation of the Gulf of Mexico Basin, the features of the deep-lying productive complex of the Norflet Formation. The second part provides information about the history of exploration of the Norflet productive complex, characteristics of the main discoveries, as well as the prospects for discoveries of new superdeep deposits in the Norflet Formation within the Gulf of Mexico (sectors of the United States and Mexico). Analysis of the history of the development of this complex by the global player Shell, is very important, as one of the scenarios for the development of deep horizons in other oil and gas basins, incl. Caspian. International Oil Companies are able to mobilize the necessary resources and technology to effectively address this challenge.

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