نتایج جستجو برای: early cretaceous
تعداد نتایج: 692756 فیلتر نتایج به سال:
Stratabound deposits within late Carboniferous carbonate units in the Middle–Lower Yangtze River metallogenic belt are important copper producers in China. Hitherto, the genesis of these deposits has been debated, due to poor constraints regarding the timing and source of the mineralization. Proposed models include a late Carboniferous seafloor exhalative formation (SEDEX), or an Early Cretaceo...
The evolutionary origin of frog crabs (Raninoida) remains puzzling partly due to their astonishing morphological disparity, ranging from broad and heavily ornamented ‘crab-like’ extinct families (necrocarcinids and allies), to elongate and smoother ‘frog-like’ extant ones (raninids and allies). However, an ancient Cretaceous clade (Palaeocorystidae) displays a combination of plesiomorphic and a...
Crocodyliforms were one of the most successful groups of Mesozoic tetrapods, radiating into terrestrial, semiaquatic and marine environments, while occupying numerous trophic niches, including carnivorous, insectivorous, herbivorous, and piscivorous species. Among these taxa were the enigmatic, poorly represented flat-headed crocodyliforms from the late Cretaceous of northern Africa. Here we re...
The timing of the origin and diversification of rodents remains controversial, due to conflicting results from molecular clocks and paleontological data. The fossil record tends to support an early Cenozoic origin of crown-group rodents. In contrast, most molecular studies place the origin and initial diversification of crown-Rodentia deep in the Cretaceous, although some molecular analyses hav...
Giant insects, with wingspans as large as 70 cm, ruled the Carboniferous and Permian skies. Gigantism has been linked to hyperoxic conditions because oxygen concentration is a key physiological control on body size, particularly in groups like flying insects that have high metabolic oxygen demands. Here we show, using a dataset of more than 10,500 fossil insect wing lengths, that size tracked a...
Diatoms are the most diverse group of algae, playing a major role in global carbon and silicon cycles (Kidder and Erwin, 2001; Armbrust, 2009) and inhabiting virtually any environment that provides moisture and sunlight (Mann, 1999). Thus, they offer important information to help reconstruct paleoen-vironments and clarify stratigraphic relationships. Their strati-graphic range extends down at l...
We analysed field-collected quantitative data of benthic marine molluscs across the Cretaceous-Palaeogene boundary in Patagonia to identify patterns and processes of biodiversity reconstruction after the end-Cretaceous mass extinction. We contrast diversity dynamics from nearshore environments with those from offshore environments. In both settings, Early Palaeogene (Danian) assemblages are str...
Understanding the formation of Qilian Shan in NE Tibetan Plateau provides insights into growth mechanisms northern portion plateau through time. The onset time exhumation is still debated. Qinghai Nan subrange, located southeastern Shan, cut by Yellow River that forms Longyang Gorge, providing a good vertical profile for thermochronological investigation exhumation. In this paper, we reconstruc...
The holotype of Brancasaurus brancai is one of the most historically famous and anatomically complete Early Cretaceous plesiosaurian fossils. It derived from the Gerdemann & Co. brickworks clay pit near Gronau (Westfalen) in North Rhine-Westphalia, northwestern Germany. Stratigraphically this locality formed part of the classic European "Wealden facies," but is now more formally attributed to t...
The sedimentary history and facies development of southern Egypt during the Latest Cretaceous Early Paleogene is summarized. G . eugubina Zone reported for first time from middle Egypt, where conglomerate usually marking a disconformity at Cretaceous/Tertiary boundary, absent. Uppermost Maastrichtian strata are attributed to M prinsii Zone, Late index foraminifer Abathomphalus mayaroensis (Boll...
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