New morphologic information on Cretaceous nannofossils from the Niobrara Formation (Upper Cretaceous) of Kansas
New morphologic information on Cretaceous nannofossils from the Niobrara Formation (Upper Cretaceous) of Kansas
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堪萨斯州尼奥布拉拉组（上白垩统）白垩纪超微化石的新形态学信息
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发表时间：
1985
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通讯作者：
M. Covington
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作者：
M. Covington
堪萨斯州西北部 Niobrara 地层的露头发现了保存完好的钙质超微化石。扫描电子和光学显微镜不仅揭示了几个新的类群，还揭示了化石记录中以前未曾描述过的非凡的圆柱形球状球。这种不寻常的圆柱形黑饼干物种也与特征性的球形球粒不同，因为它的粒石以有序和重复的方式排列。这里提出了一个新术语“cocco圆柱体”，作为比圆柱体的球球更合适的描述性术语。在尼奥布拉拉沉积期间普遍存在的停滞、缺氧的底栖环境增强了单一特异性球石簇的保存，这些球石簇代表了在脱节之前沉降到底部的球石球（通常通过粪便颗粒）。这些簇代表 34 个不同的物种，提供了有关活细胞上最初存在的颗石石最少数量的信息。这些数据对于根据化石记录中单个石珊瑚的丰度确定现有种群的总生物量可能很有价值。
Outcrops of the Niobrara Formation from northwestern Kansas have yielded horizons of well-preserved calcareous nannofossils. Scanning electron and light microscopy have revealed not only several new taxa but also an extraordinary cylindrical coccosphere not previously described from the fossil record. This unusual cylindrical form of a species of Biscutum Black also differs from the characteristic spherical coccosphere by the arrangement of its coccoliths in an ordered and repetitive fashion. A new term “coccocylinder” is proposed here as a more appropriate descriptive term than coccosphere for the cylinder. A stagnant, anoxic benthic environment prevalent during intervals of Niobrara deposition enhanced the preservation of monospecific coccolith clusters which represent coccospheres that settled to the bottom (often via fecal pellets) before disarticulating. These clusters, representing 34 different species, provide information on the minimum number of coccoliths originally present on the living cell. Such data may be valuable for determining the total biomass of the living populations on the basis of the abundances of individual coccoliths in the fossil record.