نتایج جستجو برای: middle cambrian
تعداد نتایج: 157317 فیلتر نتایج به سال:
Cambrian trees are oriented and labeled trees which fulfill local conditions around each node generalizing the conditions for classical binary search trees. Based on the bijective correspondence between signed permutations and leveled Cambrian trees, we define the Cambrian Hopf algebra generalizing J.-L. Loday and M. Ronco’s algebra on binary trees. We describe combinatorially the products and ...
The Cambrian appearance of fossils representing diverse phyla has long inspired hypotheses about possible genetic or environmental catalysts of early animal evolution. Only recently, however, have data begun to emerge that can resolve the sequence of genetic and morphological innovations, environmental events, and ecological interactions that collectively shaped Cambrian evolution. Assembly of ...
BACKGROUND Extant cubozoans are voracious predators characterized by their square shape, four evenly spaced outstretched tentacles and well-developed eyes. A few cubozoan fossils are known from the Middle Cambrian Marjum Formation of Utah and the well-known Carboniferous Mazon Creek Formation of Illinois. Undisputed cubozoan fossils were previously unknown from the early Cambrian; by that time ...
The hyolith fauna of the middle Bystraya Formation (Cambrian Series 2) eastern Transbaikalia (Zabaykalsky Krai), Siberia, includes at least 17 described taxa distributed between orders Hyolithida and Orthothecida. Species Microcornus, Parkula, Conotheca, Neogloborilus Cupitheca are widely reported from Cambrian strata elsewhere. Triplicatella uslonica sp. nov. is known only Transbaikalia. Dauri...
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