摘要
描述了陕西南郑梁山上奥陶统南郑组及临湘组的三叶虫 Kweichowilla liangshanensis sp. nov.,Triarthrus sp. 及 ? Aspidaegalina liangshanensis Chen (sp. nov.).前两者产于南郑组,后者产于临湘组.Kweichowilla 属系首次在陕西上奥陶统发现,Aspidaegalina 属在我国上奥陶统也是首次见及.
The present paper deals with the trilobites Kweichowilla liangshanensis sp. nov., Triarthrus sp. and
Aspidaegalina liangshanensis Chen (sp. nov.), with the first two species occurring in the Nanzheng Formation and the last one in the Linxiang Formation. All the species are first dissovered from the Upper Ordovician in Liangshan district of Nanzheng, Shaanxi. DESCRIPTION OF NEW SPECIES Family Shumardiiae Lake, 1907 Genus Kweichowilla Chang, 1974 Kweichowilla liangshanensis sp. nov. (Pl. I, figs. 1-3, 5, 8, 9, 11-13) Description Cephalon transversally semielliptical, slightly convex, without frontal and lateral furrows. Glabella urceolate, with a length of 4/5 the width of cephalon, bearing an anterior glabellar tongue contracted in the middle part; glabellar furrows faint. Occipital furrow shallow and narrow, gently curved forward; occipital ring long, protruding backward. Axial furrows narrow and shallow, divergent from occipital furrow, becoming convergent while reaching 1/3 the length of glabella till the margin of cephalon. Genae 1/2 as wide as glabella, with a pair of acute genal angles. Posterior border broad, narrowing toward lateral extremities. Posterior border furrows narrow and deep. Thorax preserved with 4 segments. Axis 1/3 as broad as thorax, narrowing backward. Axial furrows deep. Second pleural segment from the posterior large, with a long pleural spine. Pleural furrows broad and deep. Pygidium transversally rectangular. Axis conical, acutely backward, 2/3 as long as pygidium, composed of 6 rings and a terminal piece. Pleurae with 4 pleural segments, without border. Surface of pygidium with few scatteredly distributed granules. Comparison The new species is similar to Kweichowilla hongyaensis, but differs from the latter in having a broader cephalon and in the contracted, instead of parallel frontal portion of the glabella. It is also similar to K. minuta, but differs from the latter in the contracted instead of conver gent frontal portion of the glabella and in the rectangular pygidium. Ho
出处
《古生物学报》
CAS
CSCD
北大核心
1992年第6期730-733,共4页
Acta Palaeontologica Sinica
关键词
晚奥陶世
陕西南郑
三叶虫纲
trilobites, Upper Ordovician, Nanzheng, Shaanxi
