نتایج جستجو برای: early maastrichtian
تعداد نتایج: 686539 فیلتر نتایج به سال:
Maastrichtian argillaceous chalks of the Ghareb Formation are widespread throughout Israel, both in exposures and subsurface. These strata contain a rich fauna foraminifera calcareous nannoplankton, allowing detailed biozonation sediments, which were deposited series basins an outer-shelf to upper-slope environment. The distribution benthonic planktonic from reference section southern Israel is...
Recent field efforts in the Mahajanga Basin of northwestern Madagascar have recovered a diverse Late Cretaceous terrestrial and freshwater vertebrate fauna, including a growing diversity of avialans. Previous work on associated bird skeletons resulted in the description of two named avialans (Rahonavis, Vorona). Other materials, including two synsacra and numerous appendicular elements, represe...
Ecological studies suggest that rare taxa are more likely to go extinct than abundant ones, but the influence of abundance on survivorship in the fossil record has received little attention. An analysis of Late Maastrichtian bivalve subgenera from the North American Coastal Plain found no evidence that survivorship is tied to abundance across the end-Cretaceous mass extinction (65 million years...
Radiolitid rudists belonging to the genera Bournonia FISCHER, Biradiolites D’ORBIGNY and Thyrastylon CHUBB are abundant in the Upper Maastrichtian, Titanosarcolites Limestones (Guinea Corn Formation and other formations) of Jamaica. Although there is a large literature on these Jamaican forms (e.g., WHITFIELD, 1897; TRECHMANN, 1924; CHUBB, 1956, 1967, 1971), little information on their microstr...
—Mesozoic marine ecosystems were dominated by several clades of reptiles, including sauropterygians, ichthyosaurs, crocodylomorphs, turtles, and mosasaurs, that repeatedly invaded ocean ecosystems. Previous research has shown that marine reptiles achieved great taxonomic diversity in the Middle Triassic, as they broadly diversified into many feeding modes in the aftermath of the Permo-Triassic ...
—Mesozoic marine ecosystems were dominated by several clades of reptiles, including sauropterygians, ichthyosaurs, crocodylomorphs, turtles, and mosasaurs, that repeatedly invaded ocean ecosystems. Previous research has shown that marine reptiles achieved great taxonomic diversity in the Middle Triassic, as they broadly diversified into many feeding modes in the aftermath of the Permo-Triassic ...
به منظور مطالعات میکروبیواستراتیگرافی و پالئواکولوژی (بر اساس داده های ژئوشیمیایی)و همچنین میکروفاسیس سازند کژدمی، مقطع کوه رحمت واقع در شمال شرق شیراز مورد مطالعه قرار گرفته است. بطور کلی این سازند با ضخامت 66/89 متر بوده که در جهت عمود بر امتداد لایه ها 76 نمونه برداشت شده و 82 مقطع میکروسکوپی از آن تهیه و مورد مطالعه قرار گرفته است. در این تحقیق مطالعات میکروبیواستراتیگرافی از دو منظر، فرامی...
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