scholarly journals A revision of the early neotheropod genus Sarcosaurus from the Early Jurassic (Hettangian–Sinemurian) of central England

2020 ◽  
Vol 191 (1) ◽  
pp. 113-149 ◽  
Author(s):  
Martín D Ezcurra ◽  
Richard J Butler ◽  
Susannah C R Maidment ◽  
Ivan J Sansom ◽  
Luke E Meade ◽  
...  
Keyword(s):  
Type Species ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Valid Species ◽  
Character State ◽  
New Information ◽  
Evolutionary Radiation ◽  
Nomina Dubia

Abstract Neotheropoda represents the main evolutionary radiation of predatory dinosaurs and its oldest records come from Upper Triassic rocks (c. 219 Mya). The Early Jurassic record of Neotheropoda is taxonomically richer and geographically more widespread than that of the Late Triassic. The Lower Jurassic (upper Hettangian–lower Sinemurian) rocks of central England have yielded three neotheropod specimens that have been assigned to two species within the genus Sarcosaurus, S. woodi (type species) and S. andrewsi. These species have received little attention in discussions of the early evolution of Neotheropoda and recently have been considered as nomina dubia. Here, we provide a detailed redescription of one of these specimens (WARMS G667–690) and reassess the taxonomy and phylogenetic relationships of the genus Sarcosaurus. We propose that the three neotheropod specimens from the Early Jurassic of central England represent a single valid species, S. woodi. The second species of the genus, ‘S. andrewsi’, is a subjective junior synonym of the former. A quantitative phylogenetic analysis of early theropods recovered S. woodi as one of the closest sister-taxa to Averostra and provides new information on the sequence of character state transformations in the lead up to the phylogenetic split between Ceratosauria and Tetanurae.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

scholarly journals Upper Karoo vertebrate assemblages (Late Triassic/Early Jurassic) of the Lake Kariba region, Zimbabwe

2017 ◽  
Author(s):  
Paul M Barrett ◽  
Tim Broderick ◽  
Kimberley Chapelle ◽  
Jonah Choiniere ◽  
Steve Edwards ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Southern Africa ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Type Locality ◽  
Late Triassic ◽  
Lake Kariba ◽  
Aquatic Fauna ◽  
Mudstone Facies

Southern Africa provides critical information on Late Triassic–Early Jurassic terrestrial tetrapod faunas. Most of the localities in this region are in South Africa and Lesotho, but preliminary work in Zimbabwe has revealed significant potential. Early Jurassic Zimbabwean localities have yielded the basal sauropodomorph Massospondylus, the early sauropod Vulcanodon and theropod material. Late Triassic localities are also known, but have yielded only fragmentary specimens thus far. In early 2017, a joint South African-Zimbabwean-UK team conducted fieldwork in the upper Karoo-aged deposits along the shores of Lake Kariba, northern Zimbabwe (Mid-Zambesi Basin). We relocated the Vulcanodon type locality on Island 126/127 and found that, contrary to previous reports suggesting a Toarcian age, the quarry was in a horizon pre-dating the onset of Drakensburg volcanism (= Batoka Basalts). It is situated instead within the earlier Lower Jurassic Forest Sandstone. This indicates that Vulcanodon is 10–15 million years older than thought previously, recalibrating several nodes within Sauropoda and indicating extensive overlap between true sauropods and 'prosauropods'. Other new vertebrate localities show that sauropodomorphs are present in the Forest Sandstone and upper Tashinga (Late Triassic) formations, but a grey mudstone facies within the Pebbly Arkose Member of the latter unit yields a more aquatic fauna, including lungfish and phytosaurs, but lacking sauropodomorphs. The phytosaur occurrence is the first in Africa south of the Sahara. Faunal and sedimentological evidence indicates that the Late Triassic and Early Jurassic sites in this region were deposited under more mesic environments than their lateral equivalents in South Africa.

Taxonomic affinities and paleogeography of Stromatomorpha californica Smith, a distinctive Upper Triassic reef-adapted demosponge

2009 ◽  
Vol 83 (5) ◽  
pp. 783-793 ◽  
Author(s):  
B. Senowbari-Daryan ◽  
G. D. Stanley
Keyword(s):  
North America ◽  
Shallow Water ◽  
Type Species ◽  
Upper Triassic ◽  
Northern Calcareous Alps ◽  
Late Triassic ◽  
Separate Species ◽  
Northern Calcareous ◽  
Siliceous Spicules ◽  
Horizontal Layers

Stromatomorpha californica Smith is a massive, calcified, tropical to subtropical organism of the Late Triassic that produced small biostromes and contributed in building some reefs. It comes from the displaced terranes of Cordilleran North America (Eastern Klamath terrane, Alexander terrane, and Wrangellia). This shallow-water organism formed small laminar masses and sometimes patch reefs. It was first referred to the order Spongiomorphidae but was considered to be a coral. Other affinities that have been proposed include hydrozoan, stomatoporoid, sclerosponge, and chambered sponge. Part of the problem was diagenesis that resulted in dissolution of the siliceous spicules and/or replaced them with calcite. Well-preserved dendroclone spicules found during study of newly discovered specimens necessitate an assignment of Stromatomorpha californica to the demosponge order Orchocladina Rauff. Restudy of examples from the Northern Calcareous Alps extends the distribution of this species to the Tethys, where it was an important secondary framework builder in Upper Triassic (Norian-Rhaetian) reef complexes. Revisions of Stromatomorpha californica produce much wider pantropical distribution, mirroring paleogeographic patterns revealed for other tropical Triassic taxa. Review of Liassic material from the Jurassic of Morocco, previously assigned to Stromatomorpha californica Smith var. columnaris Le Maitre, cannot be sustained. Species previously included in Stromatomorpha are: S. stylifera Frech (type species, Rhaetian), S. actinostromoides Boiko (Norian), S. californica Smith (Norian), S. concescui Balters (Ladinian-Carnian), S. pamirica Boiko (Norian), S. rhaetica Kühn (Rhaetian), S. stromatoporoides Frech, and S. tenuiramosa Boiko (Norian). Stromatomorpha rhaetica Kühn described from the Rhaetian of Vorarlberg, Austria shows no major difference from S. californica. An example described as S. oncescui Balters from the Ladinian-Carnian of the Rarau Mountains, Romania, is very similar to S. californica in exhibiting similar spicule types. However, because of the greater distance between individual pillars, horizontal layers, and the older age, S. oncescui is retained as a separate species. The net-like and regular skeleton of Spongiomorpha sanpozanensis Yabe and Sugiyama, from the Upper Triassic of Sambosan (Tosa, Japan), suggests a closer alliance with Stromatomorpha, and this taxon possibly could be the same as S. californica.

Upper Triassic corals from Nevada, western North America, and the implications for paleoecology and paleogeography

2013 ◽  
Vol 87 (5) ◽  
pp. 934-964 ◽  
Author(s):  
Ewa Roniewicz ◽  
George D. Stanley
Keyword(s):  
New Species ◽  
Type Species ◽  
New Genus ◽  
Upper Triassic ◽  
Late Triassic ◽  
Western North America ◽  
North American Cordillera ◽  
Coral Fauna ◽  
Taxonomic Analysis ◽  
The North

Late Carnian–early Norian corals from the Luning and Osobb formations in west-central Nevada represent an important Late Triassic fauna for understanding the paleoecology and the paleogeography of the eastern Panthalassa region during Late Triassic time. The corals occur in bedded limestone representing biostromes and patch reefs and their composition presages the important global changeover of faunas of the intra-Norian interval. A taxonomic analysis of over 60 specimens reveals a majority of colonial corals ranging from cerioid, astreoid (i.e., cerioid-plocoid lacking walls), meandroid and thamnasterioid types. Surprisingly, remnants of the original aragonite microstructure remain in some specimens, allowing a better comparison with more remote Tethyan corals. In total, 14 genera have been identified from Nevada while two genera remain undetermined. The fauna is composed of species considered typical of both the North American Cordillera and cratonal South America. The following genera and species are new and endemic to the Americas:Khytrastrea silberlingiandK. cuifiamorpha,Flexastrea serialis,Nevadoseris punctata,Areaseris nevadaensisand a new genusMinasteria(withAstrocoenia shastensisSmith, 1927 as type species). Likewise are the new species:Margarogyra silberlingiandCurtoseris dunlapcanyonae. GeneraMeandrovolzeia,Margarogyra,Ceriostella,Ampakabastraea,Retiophyllia,Distichomeandra,Curtoseris,ThamnasteriaandAstraeomorphaprovide important links to the former Tethys province. The revised coral fauna changes previous views of the close taxonomic similarity with the Tethys, instead producing a paleogeographic pattern emphasizing a much greater degree of endemism. This pattern emphasizes the isolation of Nevada from the Tethys and the similarities with some outboard terranes of the Cordillera.

Revised stratigraphy of the Takla Group, north-central British Columbia

1977 ◽  
Vol 14 (2) ◽  
pp. 318-326 ◽  
Author(s):  
J. W. H. Monger ◽  
B. N. Church
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Late Triassic ◽  
North Central ◽  
Volcaniclastic Rocks ◽  
Jurassic Rocks

The Takla Group of north-central British Columbia as originally defined contained volcanic and sedimentary rocks of Late Triassic and Jurassic ages. As redefined herein, it consists of three formations in the McConnell Creek map-area. Lowest is the Dewar Formation, composed of argillite and volcanic sandstone that is largely the distal equivalent of basic flows and coarse volcaniclastic rocks of the Savage Mountain Formation. These formations are overlain by the volcaniclastic, basic to intermediate Moosevale Formation. These rocks are Upper Triassic (upper Karnian and lower Norian). They are unconformably overlain by Lower Jurassic rocks of the Hazelton Group.

Late Triassic megalodontids (Bivalvia) from the headwaters of the Yangtze River, Qinghai province, west China

2007 ◽  
Vol 81 (6) ◽  
pp. 1327-1347 ◽  
Author(s):  
Huazhou Yao ◽  
Renjie Zhang ◽  
John Pojeta ◽  
Jinggen Sha ◽  
Jianxiong Wang
Keyword(s):  
New Species ◽  
Yangtze River ◽  
Type Species ◽  
Upper Triassic ◽  
Late Triassic ◽  
The Yangtze River ◽  
External Appearance ◽  
West China ◽  
Qinghai Province

A bivalve faunule of six species is described from the Upper Triassic Jiapila Formation at the headwaters of the Yangtze River, southern Qinghai, China. The new species, Neomegalodon cornutus and Quemocuomegalodon circularis, are described. The type species of Quemocuomegalodon, Q. orientus, is revised. Quemocuomegalodon orientus Yao, Sha, and Zhang (2003) is now known from abundant, well-preserved specimens that show great variation in shape, size, thickness of shell, and dentition, and the species Q. longitatus, Yao, Sha, and Zhang (2003) is now placed in synonymy with Q. orientus. There are significant morphologic differences between the external appearance of shelled specimens and the internal molds of species of Quemocuomegalodon. This suggests the need for the re-evaluation of many megalodontid species from elsewhere that are known only from internal molds.

scholarly journals Biomarker distributions and depositional environments of continental source rocks in Sichuan Basin, SW China

2020 ◽  
Vol 38 (6) ◽  
pp. 2296-2324
Author(s):  
Siqin Huang ◽  
Guosheng Xu ◽  
Fanghao Xu ◽  
Wei Wang ◽  
Haifeng Yuan ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Depositional Environments ◽  
Source Rocks ◽  
Late Triassic ◽  
Ms Analysis ◽  
Continental Source ◽  
The Sichuan Basin ◽  
Tricyclic Terpanes

In order to study the distributions of the biomarker of the continental source rocks in the Sichuan Basin, 71 source rock samples were collected from the Upper Triassic-Lower Jurassic strata in different regions. The n-alkanes, isoprenoids, terpane, sterane, sesquiterpenes, caranes and aromatics in the extracts were analyzed in detail. GC-MS analysis has been conducted to analyze the biomarker of the continental source rocks. The results of GC-MS analysis indicate that the Upper Triassic source rocks are high in the content of extended tricyclic terpanes, pristane, phytane, gammacerane, C28 regular sterane and carotene. However, they are low in content of rearranged compounds. The ratio of Pr/Ph is less than 1, with the characteristics of tricyclic terpane C21 > C23. The Lower Jurassic source rocks are extremely low in content (even zero) of extended tricyclic terpanes, pristane, phytane, gammacerane, C28 regular sterane and carotene, and high in content of rearranged compounds. The ratio of Pr/Ph is more than 1, with tricyclic terpane C21 > C23. These characteristics are still preserved after maturation. Moreover, during the sedimentation of the source rocks of T3x2–T3x3 members, the supply of continental plants was low (TAR < 1, with regular sterane C27 > C29, 1-MP/9-MP < 1). The source rocks of T3x5 member were low in salinity (slightly low content of gammacerane and carotene), being different significantly from the other Upper Triassic source rocks. In addition, during the sedimentation of the source rocks of J1dn Member, the supply of continental plants was also low (regular sterane C27 > C29, 1-MP/9-MP < 1), being quite different from that of J1l member. Through analysis of the difference in biomarkers, it is indicated that the sedimentary environment had changed from anoxic and brackish water during the Late Triassic to oxygen-rich and freshwater during the Early Jurassic in the Sichuan Basin. During this process, the types of organic matters had changed for several times.

scholarly journals Upper Karoo vertebrate assemblages (Late Triassic/Early Jurassic) of the Late Kariba region, Zimbabwe

2017 ◽  
Author(s):  
Paul M Barrett ◽  
Tim Broderick ◽  
Kimberley Chapelle ◽  
Jonah Choiniere ◽  
Steve Edwards ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Southern Africa ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Type Locality ◽  
Late Triassic ◽  
Lake Kariba ◽  
Aquatic Fauna ◽  
Mudstone Facies

Southern Africa provides critical information on Late Triassic–Early Jurassic terrestrial tetrapod faunas. Most of the localities in this region are in South Africa and Lesotho, but preliminary work in Zimbabwe has revealed significant potential. Early Jurassic Zimbabwean localities have yielded the basal sauropodomorph Massospondylus, the early sauropod Vulcanodon and theropod material. Late Triassic localities are also known, but have yielded only fragmentary specimens thus far. In early 2017, a joint South African-Zimbabwean-UK team conducted fieldwork in the upper Karoo-aged deposits along the shores of Lake Kariba, northern Zimbabwe (Mid-Zambesi Basin). We relocated the Vulcanodon type locality on Island 126/127 and found that, contrary to previous reports suggesting a Toarcian age, the quarry was in a horizon pre-dating the onset of Drakensburg volcanism (= Batoka Basalts). It is situated instead within the earlier Lower Jurassic Forest Sandstone. This indicates that Vulcanodon is 10–15 million years older than thought previously, recalibrating several nodes within Sauropoda and indicating extensive overlap between true sauropods and 'prosauropods'. Other new vertebrate localities show that sauropodomorphs are present in the Forest Sandstone and upper Tashinga (Late Triassic) formations, but a grey mudstone facies within the Pebbly Arkose Member of the latter unit yields a more aquatic fauna, including lungfish and phytosaurs, but lacking sauropodomorphs. The phytosaur occurrence is the first in Africa south of the Sahara. Faunal and sedimentological evidence indicates that the Late Triassic and Early Jurassic sites in this region were deposited under more mesic environments than their lateral equivalents in South Africa.

scholarly journals New material and revision ofMelanorosaurus thabanensis, a basal sauropodomorph from the Upper Triassic of Lesotho

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1639 ◽  
Author(s):  
Claire Peyre de Fabrègues ◽  
Ronan Allain
Keyword(s):  
Phylogenetic Analysis ◽  
Southern Africa ◽  
Upper Triassic ◽  
Early Jurassic ◽  
Type Locality ◽  
Late Triassic ◽  
Original Publication ◽  
Stratigraphic Position ◽  
New Material

Melanorosaurusis a genus of basal sauropodomorph that currently includes two species from Southern Africa. In this paper, we redescribe the holotype femur ofMelanorosaurus thabanensisfrom the Elliot Formation of Lesotho, as well as associated remains. The stratigraphic position of this taxon is reviewed, and it is clear that it comes from the Lower Elliot Formation being, therefore, Late Triassic in age, and not Early Jurassic as originally described. The knowledge of the anatomy of the basal sauropodomorph of Thabana Morena is enhanced by the description of six new skeletal elements from the type locality. The femur and the ilium from Thabana Morena are diagnostic and characterized by unusual proportions. The first phylogenetic analysis including both this specimen andMelanorosaurusis conducted. This analysis leads to the conclusion that the femur described in the original publication ofMelanorosaurus thabanensiscan no longer be referred toMelanorosaurus. For these reasons, we hereby createMeroktenosgen. nov. to encompassMeroktenos thabanensiscomb. nov.

Chapter 14: The Brucejack Au-Ag Deposit, Northwest British Columbia, Canada: Multistage Porphyry to Epithermal Alteration, Mineralization, and Deposit Formation in an Island-Arc Setting

2020 ◽  
pp. 289-311
Author(s):  
Warwick S. Board ◽  
Duncan F. McLeish ◽  
Charles J. Greig ◽  
Octavia E. Bath ◽  
Joel E. Ashburner ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Island Arc ◽  
Late Triassic ◽  
Low Grade ◽  
Coarse Aggregates ◽  
History Of ◽  
Arc Setting ◽  
Mineral District

Abstract The Brucejack intermediate-sulfidation epithermal Au-Ag deposit, located 65 km north of Stewart, BC, forms part of a well-mineralized, structurally controlled, north-south gossanous trend associated with Early Jurassic intrusions straddling the Late Triassic-Early Jurassic Stuhini-Hazelton Group unconformity in the Sulphurets mineral district. Mining of the deposit commenced in mid-2017 after a long history of exploration dating back to the 1880s. Mineralization is hosted in deformed Lower Jurassic island-arc volcanic rocks of the Hazelton Group exposed on the eastern limb of the Cretaceous McTagg anticlinorium. High-grade Au-Ag mineralization was formed from ~184 to 183 Ma in association with a telescoped, multipulsed magmatic-hydrothermal system beneath an active local volcanic center. Precious metal mineralization occurs as coarse aggregates of electrum and silver sulfosalts in steeply dipping, E- to SE-trending quartz-carbonate vein stockwork zones cutting low-grade intrusion-related phyllic alteration. Epithermal vein development is interpreted to have occurred during the waning stages of Early Jurassic sinistral transpression in a compressive arc environment, followed by a limited Cretaceous deformation overprint.

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