Cambrian Radiolaria from the Georgina Basin, Queensland, Australia
Cambrian Radiolaria from the Georgina Basin, Queensland, Australia
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DOI：
10.2307/1486119
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发表时间：
1999-01
影响因子：
1.5
通讯作者：
Mun-zu Won;R. Below
中科院分区：
文献类型：
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作者：
Mun-zu Won;R. Below
保存完好的中寒武纪放射虫是从澳大利亚乔治娜盆地的甲壳虫溪地层、印加地层和德文库尔石灰岩中发现的。与之前报道的早古生代放射虫不同，这些中寒武世放射虫与同一动物群中出现的硅质海绵针状体有两个共同的诊断特征：它们的骨骼元素由空心管组成，当存在针状体时，所有针状骨骼，包括内部针状体，都是以点为中心的。动物群包含6个新属和18个新种；它们大多数都有一根或多根针状骨骼。两个新家庭成立了。一科具有球形壳壁，具有一个或多个以点为中心的内部骨针；它在这里被命名为Archeoentactiniidae n.家人。由三个新属组成：Archeoentactinia、Fungomacula 和 Spongomassa。另一个新科，Palaeospiculumidae n. fam.，由点中心针状骨架组成，没有球壳囊；该科由单一属 Palaeospiculum n. 组成。将军属于该科的类群可能被认为是海绵骨针，但它们与海绵骨针不同，因为它们的骨架具有与古珊瑚科相同的基本结构，即骨针由顶端射线和基部射线组成。除了属于这两个科的这些属之外，还存在其他两个属。它们并不常见，并且在科一级的分类地位不确定。两者之一，Aitchisonellum n. gen.，有一个球形外壳，没有内部骨针，但它既不属于Inaniguttidae Nazarov and Ormiston 1984，也不属于Palaeoactinosphaeridae Noble 1994；它似乎最适合古放线菌科霍尔兹沃斯（Palaeoactinomiids Holdsworth，1977）的非正式群体。另一个属，Protobiramus n。 gen.，没有典型的内部骨针，但由双轴排列的四射线骨针和这些射线的反复分叉的分支组成；分支提示不合并。所检查的三个中寒武纪地层的动物群组成差异并不大：甲壳虫溪地层、印加地层和德文古石灰岩动物群分别由 7 种、23 种和 8 种组成。
Well-preserved Middle Cambrian radiolarian were recovered from the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone, Georgina Basin, Australia. Unlike previously reported Early Paleozoic radiolarians, these Middle Cambrian Radiolaria have two diagnostic characteristics in common with siliceous sponge spicules that occur in the same faunas: their skeletal elements consist of hollow tubes, and when a spicule is present, all spicular skeletons, including the internal spicule, are point-centered. The faunas contain 6 new genera and 18 new species; most of them have one or more spicular skeletons. Two new families are established. One family has a spherical shell wall with one or more point-centered internal spicule(s); it is named here Archeoentactiniidae n. fam. and consists of three new genera, Archeoentactinia, Fungomacula, and Spongomassa. The other new family, Palaeospiculumidae n. fam., consists of a point-centered spicular skeleton without a spherical shell capsule; the family is composed of the single genus Palaeospiculum n. gen. The taxa belonging to this family might perhaps be considered to be sponge spicule, but they differ from sponge spicule because their skeleton has the same basic structure as in Palaeoscenidiidae, that is, the spicule consists of apical and basal rays. In addition to these genera belonging to the two families, two other genera are present. They are uncommon and are of uncertain taxonomic position at the family level. One of the two, Aitchisonellum n. gen., has a spherical shell without internal spicule, but it belongs to neither Inaniguttidae Nazarov and Ormiston 1984 nor Palaeoactinosphaeridae Noble 1994; it seems to fit best in the informal group of Palaeoactinomiids Holdsworth (1977). The other genus, Protobiramus n. gen., has no typical internal spicule, but consists of a biaxially arranged four-rayed spicule and repeatedly bifurcated branches of those rays; the branch tips are not merged. The difference in faunal compositions among the three Middle Cambrian formations examined is not great: the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone faunas consist of 7, 23, and 8 species, respectively.