| 论似发珊瑚(Pilophyllia Ge et Yü,1974)的分类位置和演化特征 |
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| ON THE TAXONOMIC POSITION AND EVOLUTIONARY TREND OF PILOPHYLLIA GE et Yü, 1974 |
| The diagnosis of the genus is supplemented in terms of septal type and minute skeletal structures. The septa of Pilophyllia are clearly amplexoid, and are composed mainly of lamellar sclerenchyme in the proximal part of the corallum, but are characterized by development of trabeculae in the upper part. The outer part of septa in the peripheral stereozone are thick and contiguous, containing stout rhabdacanth trabeculae invested with lamellar tissue. The septa grow suddenly thin beyond the stereozone, but still comprise rhabdacanth trabeculae that are developed upon the successive tabular floors.The clear boundary and evident difference between the juxtaposed and well-preserved lamellar and fibrous tissue as seen within the septa indicate that the idea of secondary origin of the lamellar structure of the skeleton is not tenable.There are altogether 14 species and subspecies of the genus, among which, the three new ones, Pilophyllia simplex Chen, P. alternata Chen and P. densi-tabulata Chen are described here. Only three species occur in the Lower Silurian. A comparison of the various species show that a clear tendency existed for the fibrous structure, i. e. the trabeculae, to develop at the expense of lamellar structures at higher horizons (PⅠ. Ⅱ, Fig. 1-4). Other evolutionary trends include thickening of the septs and increasing width of the stereozone.On the basis of skeletal structures, Pilophyllia is attributed to Family Amplexidae, which is characterized by amplexoid septa and progressive development of fibrous skeletal structures. Two groups may be recognized in the family,a primary group dominated by the lamellar tissue of septa throughout, including Amplexoides, Lindstroemophyllum, probably also Zelophyllum and the Late Ordovician compound form Crenulites, in addition to the Carboniferous Amplexus and Bordenia, and an advanced group with a progressive development of trabeculate septa, including Pilophyllia and Protopilophyllum. The Devonian Si phono phrentis and Heterophrentis with complete septa may not be included in this family. |
| WANG Hong-zhen,HE Xin-yi,CHEN Jian-qiang.1986.ON THE TAXONOMIC POSITION AND EVOLUTIONARY TREND OF PILOPHYLLIA GE et Yü, 1974[J].Acta Geoscientica Sinica,8(1):95-105. |
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