龙门山北段早泥盆世Polygnathus的演化和古生态

龙门山北段早泥盆世牙形石动物群和Polygnathus的面貌与澳大利亚等地有惊人的相似之处。由Polygnathus dehiscens dehiscens→P.nothoperbonus→P.inversus→P.serotinus,以及由P.perbonus→P.labiosus→P.declinatus(=“P.pseudoserotinus”)的演化路线已经观察到。该序列主要繁盛于底栖相区。即使在同一生物地理区内,Polyg-nathus各分子的分布也受到相的控制,从而形成不同的演化路线。该文还简要描述了几个重要属种,其中有一新种和一未定种。

LINEAGES AND PALEOECOLOGY OF EARLY DEVONIAN Polygnathus AT THE NORTHERN PART OF LONGMENSHAN AREA

The early Devonian conodont faunas and the genus Polygnathus at the northern part of Longmenshan area resemble greatly those of Australia and some other areas. The evolutionary trends from Polygnathus dehiscens dehiscens-P. nothoperbonus-P. inversus-P. serotinus and from P. perbonus-p. labiosus-P. declinatus (= "P. pseudoperotinus") are observed. This similarity indicates that do exist the biogeographical provinces in early Devonian, and the sequences listed abeve probably flourished mainly in benthic facies. Even within the same biogeographical province, the distribution of the Polygnathus elements was subjected to facies conditions, ang thus evolved the different evolutionary branches. One new species (Ozarkondina beichuanensis) is described. Ozarkodina sp. A is kept in open nomenclature.