نتایج جستجو برای: some jurassic and cretaceous sediments sub
تعداد نتایج: 16973334 فیلتر نتایج به سال:
Pterosaurs reached only modest sizes in the Triassic-Jurassic. By contrast, Cretaceous saw a trend toward large to giant size (2 m >6 wingspans), and while small-medium (<1 m–2 wingspans) sized forms are known from Lower they rare Upper Cretaceous. This pattern has been ascribed appearance of birds mid-Mesozoic, their displacement pterosaurs niches previously occupied by forms. Here we show how...
The Upper Cretaceous Lokoja Formation of southern Niger Basin in Nigeria is a dominantly sandy facies comprising of two distinctive members, the Lokoja and Patti Siltstone. The fluvial sandstone of the Lokoja Sandstone is petrologically defined as dominantly poorly sorted angular to sub-angular, fine to aly skewed, immature lithic arkose to sub-litharenite with a detrital clayey matrix of over ...
The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10(2) or 10(3) years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The...
Two multituberculate molars from the Kimmeridgian of the Langenberg Quarry near Goslar (Lower Saxony, Germany) represent the first Jurassic mammals from Germany. An upper M1 with cusp formula 5L/4B is characterized by strongly ornamented enamel and is assigned to Teutonodon langenbergensis gen. et sp. n. within the plagiaulacid line. A second specimen preserving two large and one small cusp is ...
Abstract Early Cretaceous and Jurassic sequences in the southwestern Iran host some of largest hydrocarbon reservoirs globe. This study is aimed at evaluating maturity fluids, migration paths, characteristics Pabdeh, Kazhdumi, Garu Sargelu source rocks this region. For purpose, 27 samples Pabdeh Kazhdumi Formations from wells northern part Dezful Embayment were chemically evaluated by Rock–Eval...
Palynological data from the Newark basin of the Newark Supergroup reveal a spike in the spore/pollen ratio at the TriasGc/Jurassic boundary. This spore spike is coincident with a 60% regional extinction of the palynoflora and approximately synchronous with terrestrial vertebrate extinctions. Orbitally controlled sedimentary cycles allow stratigraphic sections to be calibrated in time, constrain...
We report the first cephalopod statoliths from Early Cretaceous. These unique microfossils fill gap in fossil record between Jurassic and Cenozoic forms, are more similar to former. compare morphology of Mesozoic forms with Recent decabrachians. This comparison shows closest resemblance Idiosepiidae. suggest that belong basal decabrachians they related idiosepiids. The belemnitid identity these...
Abstract The Jiaguan Formation and the underlying Feitianshan (Lower Cretaceous) in Sichuan Province yield multiple saurischian (theropod–sauropod) dominated ichnofaunas. To date, a moderate diversity of six theropod ichnogenera has been reported, but none these have identified at ichnospecies level. Thus, many morphotypes common “generic” labels such as Grallator , Eubrontes, cf. Eubrontes or ...
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