نتایج جستجو برای: middle cretaceous
تعداد نتایج: 163403 فیلتر نتایج به سال:
The role of niche specialization and narrowing in the evolution and extinction of the ichthyosaurs has been widely discussed in the literature. However, previous studies have concentrated on a qualitative discussion of these variables only. Here, we use the recently developed approach of quantitative ecospace modelling to provide a high-resolution quantitative examination of the changes in diet...
Growing evidence of morphological diversity in angiosperm flowers, seeds and pollen from the mid Cretaceous and the presence of derived lineages from increasingly older geological deposits both imply that the timing of early angiosperm cladogenesis is older than fossil-based estimates have indicated. An alternative to fossils for calibrating the phylogeny comes from divergence in DNA sequence d...
The head and mouthpart structures of 11 species of Eurasian scorpionflies represent three extinct and closely related families during a 62-million-year interval from the late Middle Jurassic to the late Early Cretaceous. These taxa had elongate, siphonate (tubular) proboscides and fed on ovular secretions of extinct gymnosperms. Five potential ovulate host-plant taxa co-occur with these insects...
Two new species, Paramesosciophilodesbellus sp. n. and Paramesosciophilodesrarissima sp. n., from the Jiulongshan Formation at Daohugou Village, Inner Mongolia, China, are described in the extinct family Mesosciophilidae. Altogether seven genera with 21 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Midd...
A new species of fossil ray spider, Baalzebub? mesozoicum n. sp. (Araneae: Theridiosomatidae), is described from Mesozoic amber from the Cretaceous (Middle Cenomanian to Early Santonian) deposits of La Garnache, Vendée, NW France. The palpal structures, especially the highly sclerotized claw-shaped retrolateral ‘paracymbium’ originating as an outgrowth of the cymbium basally and the basal cymbi...
Based on a review of troodontid specimens from the territories of the former Soviet Union, including new discoveries from Uzbekistan, two dental morphotypes can be distinguished among Troodontidae from the Cretaceous of Asia: (1) unserrated teeth, present in Mei from Lujiatun (China; Early Cretaceous: Hauterivian-Barremian), an unnamed taxon from Hövöör (Mongolia; Early Cretaceous: Aptian-Albia...
new simplified tectonic models and depositional history of late cretaceous rocks are established in a part of zagros orogenic belt that is located in the northeastern iraq. these rocks constutes the most important cretaceous oil reservoir in the middle east. the dependent tools are petrography, field study and the concept of drowning phases. this concept is relatively new and accurate in explan...
This report summarizes the international divisions and ages in the Geologic Time Scale, published in 2012 (GTS2012). Since 2004, when GTS2004 was detailed, major developments have taken place that directly bear and have considerable impact on the intricate science of geologic time scaling. Precam brian now has a detailed proposal for chronostratigraphic subdivision instead of an outdated and ab...
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