小嘴贝类腕足动物Planovatirostrum形态奇特,在我国,目前仅在新疆北部和布克赛尔蒙古族自治县和什托洛盖镇北10余公里处七里沟剖面洪古勒楞组中段底部层位中发现,化石大致呈簇状密集或花斑状分布。经过对产Planovatirostrum planoovale岩性、岩相和生物相的综合分析得知,这段地层是一套深水相沉积,P.pla-noovale生活在水体宁静、海水较深的软质基底上。

The Late Devonian Hongguleleng Formation, widespread in northern Xinjiang, consists mainly of thin-bedded marl, bioclastic packstone, volcaniclastics, siliceous rock, siltstone clastics and limestones. This formation has its type locality 3km W of Boulongour Reservoir, and 30km N of Hoxtolgay in the Mongolian Autonomous County of Hoboksar. Many organisms went into extinction during the Kellwasser Events, especially the Upper Kellwasser Event at the Frasnian-Famennian boundary, but many groups of organisms which were thought to have gone into extinction at that time acturally occur in the Hongguleleng Formation including abundant conodonts, brachiopods, rugosal corals, echinoderms, chitinozoans,bryozoans, trilobites and gastropods as well as miospores and acritarchs. The rhynchonellid brachiopod Planovatirostrum is only found in the lower part of the middle member of the Hongguleleng Formation in the Qiligou section and characterized by transversely ovate outline, flatterned to weakly biconvex, small ventral foramen, fold and sulcus low and wide, weak plications from the middle part to the anteriors of shells, smoothly in the posterior of shells. It is easily to distinguish Planovatirostrum from other genera of rhynchonellids by its special outline and other characters. The specimens of P. planoovale are completely preserved as clusters or spots in the Hongguleleng Formation, and the species might have been living in the deeper water environment by free resting on the substrate where was quiet-water, poor food, and unfavourable for the most benthic organisms.

Q915.816 Q914.81

中国科学院资助项目 , 国家重点基础研究发展计划(973计划)