نتایج جستجو برای: middle cretaceous
تعداد نتایج: 163403 فیلتر نتایج به سال:
The Coleoptera (beetles) constitute almost one-fourth of all known life-forms on earth. They are also among the most important pollinators of flowering plants, especially basal angiosperms. Beetle fossils are abundant, almost spanning the entire Early Cretaceous, and thus provide important clues to explore the co-evolutionary processes between beetles and angiosperms. We review the fossil recor...
The fossil record of Australian dinosaurs in general, and theropods in particular, is extremely sparse. Here we describe an ulna from the Early Cretaceous Eumeralla Formation of Australia that shares unique autapomorphies with the South American theropod Megaraptor. We also present evidence for the spinosauroid affinities of Megaraptor. This ulna represents the first Australian non-avian therop...
Stereotyped feeding damage attributable solely to rolled-leaf hispine beetles is documented on latest Cretaceous and early Eocene ginger leaves from North Dakota and Wyoming. Hispine beetles (6000 extant species) therefore evolved at least 20 million years earlier than suggested by insect body fossils, and their specialized associations with gingers and ginger relatives are ancient and phylogen...
The Jura-Cretaceous coal seams of the Currier, Mist Mountain, &thing and Gates formations generally formed in delta or strand plain environments with little marine influence. The sulphur contents of coal from these formations is therefore generally low, nearly always less than I % and often less than 0.5 %. Coalbearing formations of the Cretaceous Nanaimo and Skeena groups were deposited in coa...
Evidence for a major extinction of insect herbivores is provided by presence-absence data for 51 plant-insect associations on 13,441 fossil plant specimens, spanning the Cretaceous/Paleogene boundary in southwestern North Dakota. The most specialized associations, which were diverse and abundant during the latest Cretaceous, almost disappeared at the boundary and failed to recover in younger st...
P. M a r í n e t a l . G e o l o g i c a A c t a , 1 2 ( 4 ) , 3 2 7 3 4 2 ( 2 0 1 4 ) D O I : 1 0 . 1 3 4 4 / G e o l o g i c a A c t a 2 0 1 4 . 1 2 . 4 . 4 Asphaltic oils from SE Basque-Cantabrian Basin, Spain 328 reported by several authors (Ramírez del Pozo, 1969; Pujalte, 1977; Salamon, 1982; Rat, 1988; Grafe and Wiedmann, 1993; Cámara, 1997; Gómez et al., 2002; Capote et al., 2002; Barno...
The terpenoid compositions of the Late Cretaceous Xixia amber from Central China and the middle Miocene Zhangpu amber from Southeast China were analyzed by gas chromatography-mass spectrometry (GC-MS) to elucidate their botanical origins. The Xixia amber is characterized by sesquiterpenoids, abietane and phyllocladane type diterpenoids, but lacks phenolic abietanes and labdane derivatives. The ...
An engraving made by a scolytid bark beetle, assigned to the genus Dendroctonus of the tribe Tomicini, has been identified on a mummified, middle Eocene (45 Ma) specimen of Larix altoborealis wood from the Canadian High Arctic. Larix altoborealis is the earliest known species of Larix, a distinctive lineage of pinaceous conifers that is taxonomically identifiable by the middle Eocene and achiev...
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