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Clarkina postbitteri和 C.dukouensis两个种的正确鉴定是确定乐平统底界的关键。 Mei和 Wardlaw(1994b,c)在建立这两个种时就已明确指出 ,C.postbitteri不同于 C.dukouensis主要是有浑圆而不是钝圆的齿台后端 ,并有明显的后边缘 (brim ) ,并不是依据齿脊特征区别的。金玉 (Jin,2 0 0 0 a)与 Henderson(2 0 0 1)强调 ,C.postbitteri的中后部细齿分离是有别于 C.dukouensis的主要特征。比较 C.postbitteri与 C.dukouensis的正模和 Mei et al.(1994c)所鉴定的 C.dukouensis(图 1a— c) ,可以清楚地看到 ,两者的齿脊几乎相同。 Mei etal.(1994c)所鉴定的 C.dukouensis齿脊的细齿甚至比 C.postbitteri的还分离 (图 1a,b)。两个种的区别 ,应保持原来的定义 :主要依齿台后端形状和后边缘的有无。Clarkina dukouensis由 C.postbitteri逐渐过渡而来 ,Henderson(2 0 0 1)认为 ,由于是逐渐过渡 ,C.dukouensis首次出现的点位就是任意选择的。然而 ,泥盆系 -石炭系界线的定义是在 Siphonodella presulcata- S.sulcata连续演化谱系中 S.sulcata的首次出现 ,无人认为 ,由于是连续演化谱系这个界线点位就是任意的。所有泥盆系的阶的金钉子都是以祖先种到定义种的演化谱系中定义种的首次出现为定义的 ,也无人认为这些?
The correct identification of two species, Clarkina postbitteri and C. dukouensis, is the key to determining the bottom of Leping. Mei and Wardlaw (1994b, c) made it clear at the time of the establishment of both species that C.postbitteri differs from C.dukouensis mainly in the rounded, rather than obtuse, posterior end of a toothed table with a distinct brim ), Is not based on the characteristics of the tooth ridge distinction. Jin Yujiao (Jin, 2000a) and Henderson (2001) emphasize that C.postbitteri’s mid-posterior serrated separation is the main characteristic that is distinct from C. dukouensis. Comparing the positive anomalies of C.postbitteri and C.dukouensis and C.dukouensis (Fig.1a-c) identified by Mei et al. (1994c), it is clear that the ridges of the two are almost the same. The fine teeth of C. dukouensis ridges identified by Mei et al. (1994c) were even separated from C.postbitteri (Fig. 1a, b). The difference between the two species should be to maintain the original definition: mainly by the back of the gear table and the rear edge of the shape of the presence or absence. Clarkina dukouensis is a gradual transition from C.postbitteri, Henderson (2001) believes that due to the gradual transition, C.dukouensis first point is arbitrarily chosen. However, the definition of the Devonian-Carboniferous boundary is the first occurrence of S.sulcata in the Siphonodella presulcata-S.sulcata continuous evolutionary lineage. No one believes that this boundary point is arbitrary due to the continuous evolutionary lineage. All of the Devonian gold nails are defined by the first occurrence of a defined species in the evolutionary lineage of an ancestral species to a defined species, and are no one else believing?