福建永安丰海晚二叠世—早三叠世早期菊石动物群及地层意义*

一、前言福建中部和西部处于东特提斯海域的东缘,晚二叠世晚期属于华夏陆地西侧局限海近滨含菊石粉砂质、泥质沉积区(周祖仁,1985)。二叠系与三叠系连续,由晚二叠世粉砂质、泥质沉积过渡为早三叠世早期的含泥质、粉砂质的碳酸盐岩沉积,含丰富的菊石。本区除雁石剖面二叠、三叠系作过比较系统的研究外(杨遵仪等,1987;吴顺宝等,1988),其他地区相当地层的系统研究做得较少。     

福建大田崆峒山晚二叠世和早三叠世介形类

报道福建大田崆峒山晚二叠世大隆组、长兴组及早三叠世溪口组介形类35属67种,其中描述8属9种(包括5新种)。产自长兴组的介形类化石被划分为3个组合,自下而上分别是：Polylites magnituberos-Or-thobairdia meishanensis-Pustulobairdia mailinensis组合,Baitrdia urodelofot-OS-orthobairdia exilimarginata-Bairdia subcontracta组合和Petasobairdia bicornuta-Neoamphissites costatus-Kegelites datianensis组合。大田崆峒山介形类动物群在二叠-三叠系界线上下具有明显的突变性质,这与世界其它地区一样,是遭受二叠纪末期的生物大灭绝事件重创所致。根据介形类化石组合特征,并参考共生或共存化石的内容,福建大田地区长兴组大致相当于浙江煤山长兴组的中、上部,长兴灰岩下伏的海相碎屑岩应划归长兴阶。大隆组、长兴组及溪口组的岩性和化石组合特征．显示古环境从滨海沼泽开始,经历浅海盆地→浅水碳酸盐台地→浅海近岸环境的演化过程。     

福建大田广平早二叠世栖霞组介形类动物群*

记述福建大田广平早二叠世栖霞组介形类化石9属16种,包括1新属9新种.将这一介形类动物群自下而上划分为4个组合:1)Bairdia menardensis-Orthobairdia xingyangensis-Bairdia dorsalta组合;2)Bairdia piscariformis-Orthobairdia ponderosa-Kellettina elongata组合;3)Bairdia cristata-Fabalicypris subtililonga-Heterobairdia datianensis组合;4)Bairdia lungtanensis-Healdianella reniformis-Silenites suborthis组合.认为组合1和组合2与江苏栖霞组介形类的下部组合相当;组合3和组合4与上部组合相当.还讨论了介形类组合与(蜒)带的对应关系.     

滇西晚石炭世一早二叠世苔藓虫

简述了4个双壳类化石组合特征及沉积环境,描述了双壳类2新属(Sichuatrigonia, Pseudoburmesia)和11新种(包括新亚种).     

福建宁化早二叠世早期的小有孔虫动物群

本文报道的福建宁化湖村早二叠世时期与StaffellaTing共生的小有孔虫动物群,在福建地区还属首次发现。该动物群计有9属20种,称为Globivalvulina-Nodosaria组合。这一小有孔虫动物群的发现,不但为福建地区栖霞组底部补充了新的化石门类,且为石炭系二叠系的划分提供了新的依据。     

广西南部二叠纪长兴期放射虫动物群

广西南宁南部柳桥区的长兴组上部硅质岩中存着精美的长兴期晚期放射虫动物群,共有24属39例,其中3个新种,其中以Latentifistularia最为常见,其次是Albaillllidae和Entactiniidae,属于二叠纪晚期的Neoalbaillella optima组合。半生生物有有孔虫、海绵骨针、腕足动物等。多数属在接近二叠纪－三叠世界线附近消失,但生物群中已出现少量三叠纪分子。     

广西隆林祥播二叠纪Armenina动物群

该文记述了广西隆林祥播中二叠统茅口阶下部(Cancellina带)的Armenina动物群,计11种,其中6新种,1个未定种。该动物群产于海相亮晶生物屑灰岩之中,属浅海生物滩相沉积环境。Armenina由Misellina演化而来,继之向Verbeekina及Paraverbeekina演进,是该演化系列中的关键环节,与其上或下亲缘属有明显差异,应视作一个独立的属,归于Verbeekinine亚科。Armenina属大多数种产于茅口阶Cancellina带,少数高级种延续至茅口阶Neoschwagerina带。文中同时论述了Armenina动物群的一般特征及演化趋向。     

新疆托克逊晚三叠世昆虫

记述了新疆托克逊晚三叠世昆虫化石14属17种。这一昆虫群代表了我国北方三叠纪昆虫的面貌,也是我国最丰富的三叠纪昆虫群之一。从其生态习性分析,这个昆虫群以生活于水中和岸边环境的种类为主,说明当时托克逊地区为一水域环境,气候也很适宜昆虫的生存。     

OSTRACODS AS MARKERS OF THE PERMIAN/TRIASSIC BOUNDARY IN THE KHUFF FORMATION OF SAUDI ARABIA

Abstract:  Ostracods are described for the first time from Permian–Triassic shallow marine sediments of the Khuff Formation of central Saudi Arabia. They were collected using a modified acetolysis technique for releasing calcareous shells from limestones that is described herein. Thirty-four species belonging to 17 genera are recognized. Two new species are described: Arqoviella arabica sp. nov. and A. khartamensis sp. nov. The ostracod fauna supports a Late Permian age for the lower Khartam Member and a probable Early Triassic age for the upper Khartam Member of the Khuff Formation of central Saudi Arabia. This suggests that the Permian/Triassic boundary is located within the Khartam Member, rather than at the major lithological break between the Midhnab and Khartam members. Palaeoecological analysis suggests that the palaeoenvironment of the Khuff Formation was shallow marine (between 1 and 50 m deep) on an internal shelf.     

湖北京山早三叠世有孔虫动物群的发现及其意义

本文首次报道了湖北京山地区早三叠世有孔虫动物群,计６属１５种,其中包括４新种,在对该动物群分析基础上,作者建立了Ａｕｌｏｔｏｒｔｕｓｃｈｉａｌｉｎｇｃｈｉａｎｇｅｎｓｉｓ－Ｄｉｃｈｏｓｐｉｒａｓｉｎｅｎｓｉｓ组合带,通过对其古生态特征及生物相研究,揭示了该动物群的生活习性与生态环境的关系,简述了该有孔虫动物群的发现在地层划分对比及油气勘探中的意义。     

AMMONOIDS ACROSS THE PERMIAN/TRIASSIC BOUNDARY: A CLADISTIC PERSPECTIVE

Abstract:  The rapid diversification of ceratitid ammonoids during the earliest Mesozoic has been taken at face value as an example of explosive radiation following the Permian/Triassic mass extinction. However, the validity of this interpretation has never been tested within a phylogenetic framework. A total evidence cladistic analysis of Mid–Late Permian and Induan (earliest Triassic) ammonoids confirms the monophyly of the Ceratitida. Partitioned phylogenetic analysis of suture line characters vs. shell shape and ornament characters confirms the importance of suture-line characters for resolving the higher taxonomy of ammonoids. When the cladogram is compared with the observed fossil record, the resultant tree implies that the divergence of a number of early Triassic lineages actually occurred during the latest Permian. If these range extensions are taken into account the ammonoid per-genus extinction rate across the Permian/Triassic boundary drops from c. 85 per cent to c. 60 per cent.