نتایج جستجو برای: late cretaceous
تعداد نتایج: 201920 فیلتر نتایج به سال:
Titanosaurian dinosaurs include some of the largest land-living animals that ever existed, and most were discovered in Cretaceous deposits of Argentina. Here we describe the first Brazilian gigantic titanosaur, Austroposeidon magnificus gen. et sp. nov., from the Late Cretaceous Presidente Prudente Formation (Bauru Group, Paraná Basin), São Paulo State, southeast Brazil. The size of this animal...
Twenty-nine mollusk species from Late Jurassic to Eocene hydrocarbon seep deposits from California (USA), Japan, New Zealand, and Barbados are described and illustrated. Twenty species belong to Gastropoda and nine to Bivalvia. Seven new species, three new genera, and one new family are introduced. The gastropod Hikidea gen. nov. includes smooth-shelled Cantrainea-like colloniins from Cretaceou...
I sland faunas are natural laboratories of evolutionary change and have long fascinated biologists. The peculiar ecological conditions on islands have frequently led to the evolution of endemic taxa that differ dramatically in body size and/or morphology from their mainland relatives. Many large animals tend to become smaller on islands, and small ones generally become larger—a phenomenon known...
The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the ...
Apatite fission-track analysis was applied to Triassic and Cretaceous sediments from the South-Iberian Continental Margin to unravel its thermal history. Apatite fission-track age populations from Triassic samples indicate partial annealing and point to a maximum temperature of around 100–110 °C during their post-depositional evolution. In certain apatites from Cretaceous samples, two different...
Statistical studies on Palynology contents of Late Cretaceous to Paleocene age Gurpi Formation in a surface section in Zagros Basin,SW Iran indicate changes in abundance, species diversity, ratio of Spiniferites to Cyclonephelium (S/C), palynological marine index(PMI) values and organic facies. These palynological variations clearly reflect fluctuations in relative sea-level and depositionalenv...
In the area SW of Arak, intrusives are emplaced into metasediments of early Mesozoic age. The intrusive rocks vary in morphology, structure and mineralogy, and exhibit various degrees of alterations; Rb-Sr geochronological data have been obtained to constrain their timing. There are three different groups of granitic rocks in the area: (a) the Astaneh intrusion, consisting of granite, biotite g...
For the microbiostratigraphical studies, a stratigraphical section (named Dareh-Goshayesh) has been selected in southeast of Maragheh, Northwestern Iran. The thickness of successions in the selected stratigraphic section is measured about 223.6 m. The mentioned studied stratigraphic section is composed of two clastic and carbonate units. This succession unconformably overlies the Lar Formation ...
for biostratigraphic studies, based on calcareous nannofossils, a thickness of 480 meters of cretaceous deposits in shushud section (north birjand) has been measured and sampled. the studied section is composed of shale, marl, marine sandstone and sandy limestone. the shale and marl units were more suitable for sampling. according to taxonomical studies, 10 genera and 25 species in shushud sect...
The Mesozoic, mid-Cretaceous (Barremian to Cenomanian) deposits of southern Croatia comprise a succession of shallow tropical-water, inner-platform deposits that formed on a Bahama-type isolated Adriatic carbonate platform in the Dinarides. This succession is dominated by benthic foraminifers and dasycladalean algae, and is exposed in a nearly continuous outcrop section on the islands and along...
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