نتایج جستجو برای: upper triassic
تعداد نتایج: 208096 فیلتر نتایج به سال:
Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian-Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian-Triassic boundary extinction by about 500...
The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian croco...
The Central Atlantic Magmatic Province (CAMP) has long been proposed as having a causal relationship with the end-Triassic extinction event (∼201.5 Ma). In North America and northern Africa, CAMP is preserved as multiple basaltic units interbedded with uppermost Triassic to lowermost Jurassic sediments. However, it has been unclear whether this apparent pulsing was a local feature, or if pulses...
BACKGROUND Archosauria and their closest relatives, the non-archosaurian archosauriforms, diversified in the Early and Middle Triassic, soon after the end-Permian extinction. This diversification is poorly documented in most Lower and Middle Triassic rock sequences because fossils of early groups of archosauriforms are relatively rare compared to those of other amniotes. The early Middle Triass...
rhaetian strata from the nayband formation of the tabas block, east- central iran, were studied palynologically. the materialexamined contained moderately diverse and well-preserved dinoflagellate cyst assemblages which lead to the identification ofrhaetogonyaulax rhaetica zone. the assigned age of this dinozone (rhaetian) is justified by plant fossils such as equisetitesarenaceus, scytophyllum...
the olang area is a part of gheshlagh-olang synclinal, which is a member of eastern alborz coal basin and is situated at a distance of70 km northeast of shahroud city. coal-bearing strata of this region are part of the shemshak group (upper triassic to lower jurassic).samples from the 9 coal seams of the olang coal deposits were collected and ashed. the aim of this study is to determine theoccu...
Abstract In terrestrial settings, the Permo-Triassic mass extinction is commonly linked to major changes in sedimentological and climatic conditions that include a switch from meandering braided fluvial systems increased aridity. We examined predominantly strata of North China reveal that, on contrary, there was little substantial change during extinction. The crisis level occurs upper Sunjiago...
Stable carbon isotopic analyses of organic carbon (d13C) in individual paleosol profiles from Permian–Triassic sequences of Antarctica reveal systematic isotopic variations with profile depth. These variations are in many cases analogous to those in modern soils, which are functions of redox conditions, soil development, and degree and type of microbial decay. In modern soils, these isotopic de...
A partial skeleton of the aetosaur Stagonolepis sp. is the first tetrapod body fossil recovered from Upper Triassic strata in Canyonlands National Park. The specimen consists of a partial tooth and numerous disarticulated vertebrae, ribs, and scutes found in the Blue Mesa Member of the Petrified Forest Formation (Chinle Group) near Upheaval Dome. Stagonolepis is an index taxon of the Adamanian ...
Elongate (m-scale), cylindrical sandstone casts are common in the Upper Triassic Zuni Mountains Formation (basal Chinle Group) in a section near Fort Wingate, west-central New Mexico. Previous authors suggested that these features were formed by the burrowing activity of lungfish. Following abandonment of this hypothesis, it was proposed that the casts are the fossilized burrows of crayfish. We...
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