نتایج جستجو برای: late campanian
تعداد نتایج: 195767 فیلتر نتایج به سال:
The age and depositional environment of the Harami Formation were reevaluated based on new larger benthic foraminiferal (LBF) data. LBF assemblage including Orbitoides medius (d'Archiac), O. megaloformis Papp Küpper, gruenbachensis Papp, Pseudomphalocyclus blumenthali Meriç, Omphalocyclus macroporus (Lamarck), Sirtina cf. orbitoidiformis Brönnimann Wirz, Hellenocyclina beotica Reichel, Lepidorb...
Diatoms are one of the most important eukaryotic primary producers in lower ecosystem; understanding their evolutionary history is therefore also important. Throughout Cenozoic hydrosphere, diatoms have flourished. However, as a result progressive diagenesis and dissolution opaline silica that forms frustules, early evolution during Cretaceous unclear, so fossil record incomplete. Largely becau...
Megaherbivorous dinosaur coexistence on the Late Cretaceous island continent of Laramidia has long puzzled researchers, owing to the mystery of how so many large herbivores (6-8 sympatric species, in many instances) could coexist on such a small (4-7 million km(2)) landmass. Various explanations have been put forth, one of which-dietary niche partitioning-forms the focus of this study. Here, we...
Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing during late Santonian/early Campanian time within t...
Here we report multiple lamniform shark teeth recovered from fluvial sediments in the (Campanian-Maastrichtian) Cerro Fortaleza Formation, Santa Cruz Province, Argentina. This small tooth assemblage is compared to various lamniform sharks possessing similar dental morphologies, including Archaeolamna, Cretalamna, Dwardius, Dallasiella, and Cretodus. Although the teeth share numerous morphologic...
حوضه رسوبی کپهداغ در شمالخاوری ایران، در ناحیهای بین مرز ایران با ترکمنستان و افغانستان واقع شده و شامل توالیهای دریایی ژوراسیک تا نئوژن میباشد. سازند آبتلخ یکی از واحدهای سنگی کرتاسه بالایی حوضه رسوبی کپهداغ است که بیشترین ضخامت را در خاور این حوضه به خود اختصاص داده است. سازند آبتلخ از لحاظ نانوفسیلهای آهکی، دارای فراوانی و غنای بسیار زیاد و دارای حفظشدگی خوب تا متوسط بوده و حاوی ج...
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