نتایج جستجو برای: cretaceous
تعداد نتایج: 9055 فیلتر نتایج به سال:
Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and...
The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evolution remain obscure because of both the small...
Fossil discoveries over the past 30 years have radically transformed traditional views of Mesozoic mammal evolution. In addition, recent research provides a more detailed account of the Cretaceous diversification of flowering plants. Here, we examine patterns of morphological disparity and functional morphology associated with diet in early mammals. Two analyses were performed: (i) an examinati...
The record of dinosaurs over the last 10 m.y. of the Cretaceous, as well as surrounding the Cretaceous-Paleogene boundary, helps to defi ne extinction scenarios. Although Late Cretaceous dinosaur fossils occur on all present-day continents, only in North America do we fi nd a terrestrial vertebrate fossil record spanning the Cretaceous-Paleogene boundary, although promising work may yield compa...
The Cretaceous-Paleogene boundary marks a critical event in mammalian evolution. Using a database of 4769 mammalian specimens from the Hell Creek and lower Fort Union formations of Garfi eld County, northeastern Montana, I quantifi ed temporal patterns of diversity and community structure to evaluate faunal dynamics during the last ~1.9 m.y. of the Cretaceous, the Cretaceous-Paleogene extinctio...
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...
Angiosperms evolved and diversified during the Cretaceous period. Early angiosperms were short-stature weedy plants thought to have increased fire frequency and mortality in gymnosperm forest, aiding their own expansion. However, no explorations have considered whether the range of novel fuel types that diversified throughout the Cretaceous also altered fire behaviour, which should link more st...
Whereas titanosaurians represent the most diverse and cosmopolitan clade of Cretaceous sauropod dinosaurs, they remain rare components of Cretaceous African faunas. Currently recognized continental African titanosaurians include Aegyptosaurus baharijensis and Paralititan stromeri from early Upper Cretaceous deposits near Bahariya Oasis, Egypt, and Malawisaurus dixeyi and Karongasaurus gittelman...
The new genus and species of scoliid wasp Araripescolia magnifica Nel, Escuillie & Garrouste, gen. et sp. nov. is described from the Early Cretaceous Crato formation in Brazil. It seems to be more closely related to the modern Campsomerinae than to the other Cretaceous Scoliidae: Archaeoscoliinae and Proscoliinae.
Ectaetia capdoliensis sp. n., first Cretaceous and oldest representative of the scatopsid subfamily Ectaetiinae, is described from the Late Albian / Early Cenomanian amber of southwestern France. This fossil demonstrates the remarkable morphological stability of these flies since at least the mid-Cretaceous. It suggests the presence of rotten wood under wet palaeoenvironment for the correspondi...
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