نتایج جستجو برای: late cretaceous
تعداد نتایج: 201920 فیلتر نتایج به سال:
for study of systematic and palaeoecology of mid-cretaceous oysters, the basab section, with 380 m thickness, west of kuhbanan, northwest of kerman, was measured and sampled. the section comprises a high diverse fauna (macro and microfossils), such as echinoids, bivalves, oysters, brachiopods, gastropods, corals, ammonites, foraminifers and ostracods. the fossils indicate late aptian- early cen...
Docodonts are aMesozoicmammal group (Synapsida:Mammaliaformes) with a fossil record from theMiddle Jurassic to the late Early Cretaceous. With highly distinctive molars for both shearing and grinding functions, docodonts are inferred to have diverse dietary adaptations, including insectivory, omnivory, and even carnivory. This group also offers the earliest-known case of mammalian swimming adap...
This paper presents a new interpretation of the geometry of Triassic alignment of J. Sidi Mahdi –J. Zitoun in Medjerda Valley Plain (Northern Tunisia) based on detailed analysis of gravity and seismic reflection data. The main results of gravity analysis do not show a distinguish gravity anomaly over Triassic evaporites bodies. The positive gravity anomaly seems to be related to the entire stru...
Until recently, it was considered axiomatic that the skull of lizards and snakes arose from that of a diapsid ancestor by loss of the lower temporal bar. The presence of the bar in the living New Zealand Tuatara, Sphenodon, was thus considered primitive, corroborating its status as a 'living fossil'. A combination of new fossils and rigorous phylogeny has demonstrated unequivocally that the abs...
Deep ocean circulation may be a significant factor in determining climate. Here, we describe two long, fully coupled atmosphere-ocean simulations with the NCAR Climate System Model (CSM) for the late Cretaceous (80 Ma). Our results suggest that higher levels of atmospheric CO2 and the altered paleogeography of the late Cretaceous resulted in a surface ocean state temperature, salinity, and circ...
The fossil record of cuttlefish, squid and octopus has received relatively little attention. Among malacologists, the opinion is widespread that these mainly softbodied coleoids have a poor fossil record. However, thanks to Konservat-Lagerst tten such as the Early Jurassic Posidonian Shales of Holzmaden (Germany), the Middle Jurassic La-Voulte-sur-Rh ne (France) and the Late Jurassic Limestones...
The fossil assemblages of the Late Cretaceous of North America are dominated by large-bodied dinosaur species. Associated skeletons of small dinosaurs are exceedingly rare, and small (<10 kg) carnivorous theropods have not previously been reported from these beds. Here, we describe a small dromaeosaurid from the 75-million-year-old Dinosaur Park Formation of Alberta, Canada. Hesperonychus eliza...
The Tertiary volcanic rocks in the north and west of Birjand are dacite; andesite, basaltic andesite, trachyandesite and rhyolite.They belong to calc- alkaline from magmatic series. Mineralogcal, petrographcal and geochemical evidence show that they have formed in active continental margins. Most andesites and dacites are appeared as volcanic domes or subvolcanic dykes that injected older units...
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...
[1] Deep-ocean circulation may be a significant factor in determining climate. Here, we describe two long, fully coupled atmosphere-ocean simulations with the National Center for Atmospheric Research Climate System Model for the Late Cretaceous (80 Ma). Our results suggest that higher levels of atmospheric CO2 and the altered paleogeography of the Late Cretaceous resulted in a surface ocean sta...
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