泥盆系和石炭系的界线,是国际上地层古生物学者长期争议的问题之一。1927年首届国际石炭纪会议曾确认爱特隆层(Etroeungt)为石炭系的最低层位;但1935年第二届国际石炭纪会议则重又决议以菊石Gattendorfia subinvalata的下限为石炭系底界。Sandberg and Ziegler等总结了近年来泥盆、石炭系分界上下地层的牙形刺,认为Siphonodella sulcata带在世界上有着广泛的地理分布,其下限又与Gattendorfia subinvalata Devonian and Carboniferous boundaries, is one of the long-standing controversial issues of the international paleontologists. In 1927, the first International Carboniferous Conference confirmed that the Etroeungt was the lowest Carboniferous. However, at the Second International Conference on Carboniferous in 1935, it was re-decided that the lower limit of Gattendorfia subinvalata would be the bottom of Carboniferous . Sandberg and Ziegler et al. Summarized the conodonts of the upper and lower Devonian and Carboniferous strata in recent years and concluded that the Siphonodella sulcata belt has a wide geographical distribution in the world, with the lower limit of the conodont of the Gattendorfia subinvalata