新疆石炭系杜内-韦宪阶界线层的牙形类POLYGNATHUS COMMUNIS GANCAOHUENSIS (新亚种)POLYGNA-THUS COMMUNIS BRANSON ET MEHL 1934的种系发生

本文提出和描述了产自我国西北新疆南部喀拉塔克剖面的一个牙形类新亚种Polygnathus communis gan-caohuensis,并根据以前出版的信息,命名了另一个新亚种P0lygnathus communis carmanae.种系发生研究揭示了Polygnathus communis Branson et Mehl的亚种对于法门阶最上部至韦宪阶地层的划分是至关重要的.此种的cari-na→gancaohuensis谱系,连同发现于喀拉塔克剖面的菊石、有孔虫和腕足动物,被认为是划分杜内-韦宪阶界线的潜在的标志化石.因此,喀拉塔克剖面有可能成为全球杜内-韦宪阶界线的一个候选层型剖面.

Polygnathus Communis Gancaohuensis subsp.nov.(Conodonta) from the Tournaisian-Visean Boundary beds of Xinjiang,NW China and the phylogeny of Polygnathus communis Branson et Mehl 1934

This paper proposes and describes a new conodont subspecies Polygnathus communis gancaohuensis from the Tournaisian-Visean boundary beds of the Karatage section in southern Xinjiang, northwestern China. Another new subspecies Polygnathus communis carmanae is also formally named on the basis of the previously published information. Phylogenetic study reveals that subspecies of Polygnaythus communis Branson et Mehl are critical to the stratigraphy of the uppermost Famennian to Visean. The carina→gancaohuensis lineage, along with index species of ammonoids, foraminifers and brachiopods, recovered from the Karatag section, is considered to be the potential criterion for defining the Tournaisian-Visean boundary. The Karatag section hence is one of the possible candidated of the global stratogype of the Tournaisian-Visean boundary.