نتایج جستجو برای: late maastrichtian
تعداد نتایج: 195833 فیلتر نتایج به سال:
Ceratopsid (horned) dinosaurs are an iconic group of large-bodied, quadrupedal, herbivorous dinosaurs that evolved in the Late Cretaceous and were largely restricted to western North America [1-5]. Ceratopsids are easily recognized by their cranial ornamentation in the form of nasal and postorbital horns and frill (capped by epiossifications); these structures show high morphological disparity ...
The Gurpi Formation, one of the geologycal units of the Zagros Basin, stretches with in the Folded Zagros in the provinces of Khuzestan, Lorestan, and Fars,in southwest Iran. In all 525 samples were collected from five stratigraphic sectiones of the Gurpi Formation in Dezful embayment Zone for studying biostratigraphy. Totally 47 species from 23 Planktonic foraminifera genera were recognized in...
in present study, diversity and relative abundance of calcareous nannofossils of the boundary between abtalkh and neyzar formations in dobaradar, kalat and chahchaheh sections were studied. taxonomical studies of calcareous nannofossils in the studied areas led to identification of 24 species in dobaradar, 27 species in kalat and 32 species in chahchaheh sections. based on identified nannofossi...
The Late Cretaceous–Early Paleogene (K–Pg) was a critical period of transition in geological time. This encompassed short-term climatic fluctuations on global scale, changes ocean circulation, and sudden large extinctions marine terrestrial organisms. In the study area, located mid to low latitudes, Cretaceous Early were very tectonically active due positioning site close collision zone two con...
Cretaceous multituberculate mammals of Europe are poorly known, as a rule represented by isolated teeth. The only exception is the Late Cretaceous (Maastrichtian) monotypic genus Kogaionon Riidulescu & Samson, 1996 from Romania, represented by a single skull, without dentaries, assigned to Kogaionidae Rhdulescu & Samson, 1996, Another kogaionid genus is Hainina Vianey-Liaud, 1979, represented b...
A calcareous nannofossils biostratigraphic study has been carried out on the chalky limestones located in South Gorgan, north of Iran. The study is aimed at determining the age and nannofossil biozonations of the well. The samples were prepared using smear slide technique. Thirty seven calcareous nannofossils species were identified and used to make biostratigraphic zonations and dating of the ...
The sedimentary record documenting the northward drift of India (Late Cretaceous to late Early Eocene) has recently provided important clues to the evolution, radiation, and dispersal of mammals. Here, we report a definitive Late Cretaceous (Maastrichtian) archaic ungulate (Kharmerungulatum vanvaleni genus et species nova) from the Deccan volcano-sedimentary sequences exposed near Kisalpuri vil...
The mesoeucrocodylian record from the Bauru Group (Paraná Basin, Brazil) comes three formations: Adamantina (Late Turonian–Early Maastrichtian), Presidente Prudente (Early Campanian–Early Maastrichtian) and Marília (Maastrichtian). These records are restricted to Early Coniacian–Early Maastrichtian. Here, we report a new crocodyliform Group, which was first of Araçatuba Formation, locality Coro...
The Pierre Shale is a marine deposit that accumulated in the Cretaceous Western Interior Seaway during the onset of Laramide tectonism in the southern Rocky Mountains region. In the eastern part of the Raton Basin near Trinidad, Colorado, ammonite biostratigraphy suggests that the base of the Pierre Shale lies within or slightly above the Lower Campanian Scaphites hippocrepis III ammonite range...
The Campanian–Maastrichtian (83–66 Ma) was a period of global climate cooling, featuring significant negative carbon-isotope (δ13C) anomalies, such as the Late Campanian Event (LCE) and the Campanian–Maastrichtian Boundary Event (CMBE). A variety of factors, including changes in temperature, oceanic circulation and gateway opening, have been invoked to explain these δ13C perturbations, but no p...
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