نتایج جستجو برای: middle cenozoic
تعداد نتایج: 157713 فیلتر نتایج به سال:
Upper abyssal to lower bathyal benthic foraminifera from Ocean Drilling Program Sites 689 (present water depth 2080m) and 690 (present water depth 29I4m) on Maud Rise (Antarctica) recorded changes in deep-water characteristics at high southern latitudes during the cenozoic. The benthic foraminiferal faunas show only minor differences as a result of the difference in water depths between the sit...
Paleontologists long have argued that the most important evolutionary radiation of mammals occurred during the early Cenozoic, if not that all eutherians originated from a single common post-Cretaceous ancestor. Nonetheless, several recent molecular analyses claim to show that because several interordinal splits occurred during the Cretaceous, a major therian radiation was then underway. This c...
Defecation in communal latrines is a common behaviour of extant mammals widely distributed among megaherbivores. This behaviour has key social functions with important biological and ecological implications. Herbivore communal latrines are only documented among mammals and their fossil record is exceptionally restricted to the late Cenozoic. Here we report the discovery of several massive copro...
A major obstacle in understanding the evolution of Cenozoic climate has been the lack of well dated terrestrial evidence from high-latitude, glaciated regions. Here, we report the discovery of exceptionally well preserved fossils of lacustrine and terrestrial organisms from the McMurdo Dry Valleys sector of the Transantarctic Mountains for which we have established a precise radiometric chronol...
Lophotidae, or crestfishes, is a family of rare deep-sea teleosts characterised by an enlarged horn-like crest on the forehead. They are poorly represented in the fossil record, by only three described taxa. One specimen attributed to Lophotidae has been described from the pelagic fauna of the middle-late Eocene Zagros Basin, Iran. Originally considered as a specimen of the fossil lophotid †Pro...
Large consumers have ecological influence disproportionate to their abundance, although this influence in food webs depends directly on productivity. Evolutionary patterns at geologic timescales inform expectations about the relationship between consumers and productivity, but it is very difficult to track productivity through time with direct, quantitative measures. Based on previous work that...
Field investigations in the northwestern segment of Greater Caucasus, a Late Cenozoic orogen, have permitted establishment two new geosites, namely Ubin and Bezeps geosites. Both represent Berriasian–Middle Valanginian (Early Cretaceous) marine deposits with abundant trace fossils. The latter are attributed to Nereites ichnofacies indicate on deep palaeoenvironments (this interpretation challen...
We report new data on oxygen isotopes in marine sulfate (d18OSO4), measured in marine barite (BaSO4), over the Cenozoic. The d18OSO4 varies by 6x over the Cenozoic, with major peaks 3, 15, 30 and 55 Ma. The d 18OSO4 does not co-vary with the d 34SSO4, emphasizing that different processes control the oxygen and sulfur isotopic composition of sulfate. This indicates that temporal changes in the d...
8 Lophotidae, or crestfishes, is a family of rare deep-sea teleosts characterised by an enlarged 9 horn-like crest on their forehead. They are poorly represented in the fossil record, by only 10 three described taxa. One specimen attributed to Lophotidae has been described from the 11 pelagic fauna of the middle-late Eocene Zagros Basin, Iran. Originally considered as a 12 specimen of the fossi...
Well-preserved siliceous plates representing multiple species of euglyphids are described from a Middle Eocene maar lake deposit located near the Arctic Circle in northern Canada. Siliceous plate morphotypes including scutiform, rectangular, hexagonal, oval and circular body forms, six apertural plate types containing from five to thirteen teeth and spine plates, are documented. Many plate type...
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