江西玉山上奥陶统凯迪阶三衢山组的丛花海绵(Corymbospongia)*

串管海绵在中–晚奥陶世经历了的首次辐射演化事件, 在北美、新南威尔士、哈萨克斯坦、西伯利亚和中国西北等地的上奥陶统地层中皆有报道, 但研究程度较低。本文系华南奥陶系串管海绵首次系统古生物学的报道, 详细描述江西玉山上奥陶统凯迪阶三衢山组的Corymbospongia (丛花海绵属)化石, 并基于C. amplia Rigby, Karl, Blodgett & Baichtal, 2005和C. mica Rigby & Potter, 1986的标本展示该属化石外壁的微孔等特征性结构, 这2个种具有跨板块的生物地理分布。综合串管海绵产出层的碳酸盐岩微相以及伴生钙藻和珊瑚化石等群落分子的指相参照, 识别C. amplia和C. mica均具有明显的生态专属性: C. amplia为造礁生物, 在小型微生物岩中出现; C. mica则代表适应于更浅水生境的平地群落代表。本研究将为从底栖生物群落角度开展扬子区生物地层学及古地理重建提供进一步的依据。     

Comparison of photosynthesis and leaf ultrastructure on two black locust (Robinia pseudoacacia L.)

Polyploidy is common in many plant species. Up to date, few studies were reported on photosynthesis and leaf anatomy of tetraploid black locust (Robinia pseudoacacia L.), which has considerable value for agriculture and forest. This study compared photosynthesis and leaf ultrastructure on two black locusts. The values of P_n and C_i in tetraploid were significantly higher than those in the corresponding diploids. Significantly lower stomata dimensions (6.0 μm in length and 2.4 μm in width) and tomatal density were observed in 4×. Leaf trichome density was statistically different between 2× and 4×. However, no substantial difference in the ultrastructure of chloroplasts and mitochondria between diploid and tetraploid was observed under any stress. These ultrastructural characteristics may contribute to tetraploid a better protection mechanism than diploid.     

From near extinction to recovery: Late Triassic to Middle Jurassic ammonoid shell geometry

The Triassic–Jurassic extinction resulted in the near demise of the ammonoids. Based on a survey of ammonoid expansion rates, coiling geometry and whorl shape, we use the Raup accretionary growth model to outline a universal morphospace for planispiral shell geometry. We explore the occupation of that planispiral morphospace in terms of both breadth and density of occupation in addition to separately reviewing the occurrence of heteromorphs. Four intervals are recognized: pre‐extinction (Carnian to Rhaetian); aftermath (Hettangian); post‐extinction (Sinemurian to Aalenian) and recovery (Bajocian to Callovian). The pre‐extinction and recovery intervals show maximum disparity. The aftermath is marked by the disappearance of heteromorphs and a dramatic reduction in the range of planispiral morphologies to a core area of the morphospace. It is also characterized by an expansion into an evolute, slowly expanding part of the morphospace that was not occupied prior to the extinction and is soon abandoned during the post‐extinction interval. Aftermath and post‐extinction ammonoid data show a persistent negative correlation whereby rapid expansion rates are associated with narrow umbilical widths and often compressed whorls. The permanently occupied core area of planispiral morphospace represents generalist demersals whose shells were probably optimizing both hydrodynamic efficiency and shell stability. All other parts of the planispiral morphospace, and the pelagic modes of life the shells probably exploited, were gradually reoccupied during the post‐extinction interval. Planispiral adaptation was by diffusion away from the morphospace core rather than by radical jumps. Recovery of disparity was not achieved until some 30 Myr after the extinction event.     

陕西横山晚三叠世鱼类游泳遗迹化石新材料

在多次赴化石产地陕西横山县进行大规模化石发掘后,获得一批完整精美的遗迹标本,为其中鱼类游泳遗迹化石标本建立了新种Undichna prava,并重新修订U.britannica,U.tricosta两种的特征,通过遗迹形态恢复鱼体长度为50—96cm,普遍大于以往描述的国内外据遗迹标本恢复的鱼体长度。     

贵州兴义晚三叠世贵州龙层新发现的鱼类

描述贵州兴义地区贵州龙层中新发现的鱼类4新属、4新种和一件新材料,它们是小鳞贵州鳕(新属、新种)Guizhouniscus microlepidus Liu gen．et sp．nov．,小短体鱼(新属、新种)Brachysomus minor Liu gen．et sp．nov．,秀丽兴义鱼(新属、新种)Xingyia gracilis Liu gen．et sp．nov．,臀鳞贵州真颌鱼(新属、新种)Guizhouella analilepidn Liu gen．et sp.nov,和优美贵州弓鳍鱼Guizhouamia bellula Liu et a1．,2002的一件新材料。新的发现和研究表明这是一个颇具特色的晚三叠世早期鱼群。文章还简要讨论各新属新种的系统分类位置和该鱼群在整个鱼类进化中的地位,着重论述贵州弓鳍鱼Guizhouamia的进化意义及弓鳍鱼科的系统发育问题。根据鱼群的特征贵州龙层的地质时代为晚三叠世。     

华南下扬子区的裂齿鱼类化石——华南二叠系—三叠系界线上下鱼类序列研究之二

重新描述了江苏句容与安徽和县的裂齿鱼类化石 ,将华南下扬子区已记述的 2属 5种裂齿鱼类化石初步修订为 1属 2种———江苏张氏鱼 (Zhanginajiangsuensis)和扬子张氏鱼(Zhanginayangtzensis)。由于目前对裂齿鱼类的系统发育关系所知甚少 ,张氏鱼属的系统位置以及相关的动物地理分布问题仍有待深入的研究。     

Biogeography of Triassic tetrapods: evidence for provincialism and driven sympatric cladogenesis in the early evolution of modern tetrapod lineages

Triassic tetrapods are of key importance in understanding their evolutionary history, because several tetrapod clades, including most of their modern lineages, first appeared or experienced their initial evolutionary radiation during this Period. In order to test previous palaeobiogeographical hypotheses of Triassic tetrapod faunas, tree reconciliation analyses (TRA) were performed with the aim of recovering biogeographical patterns based on phylogenetic signals provided by a composite tree of Middle and Late Triassic tetrapods. The TRA found significant evidence for the presence of different palaeobiogeographical patterns during the analysed time spans. First, a Pangaean distribution is observed during the Middle Triassic, in which several cosmopolitan tetrapod groups are found. During the early Late Triassic a strongly palaeolatitudinally influenced pattern is recovered, with some tetrapod lineages restricted to palaeolatitudinal belts. During the latest Triassic, Gondwanan territories were more closely related to each other than to Laurasian ones, with a distinct tetrapod fauna at low palaeolatitudes. Finally, more than 75 per cent of the cladogenetic events recorded in the tetrapod phylogeny occurred as sympatric splits or within-area vicariance, indicating that evolutionary processes at the regional level were the main drivers in the radiation of Middle and Late Triassic tetrapods and the early evolution of several modern tetrapod lineages.     

中国陕西铜川中三叠世二叠澳蝎蛉科新属新种(昆虫纲,长翅目)

记述中国陕西铜川中三叠世1新属和1新种。化石采自铜川中三叠世铜川组下段上部灰绿色泥页岩。根据脉序特征,新属、新种应归于二叠澳蝎岭科Permochoristidae,新属种的名称为Qingochorista conjunctiva gen.et sp．nov．,属于陕西昆虫群(系中三叠世陕西生物群的一个化石门类)铜川昆虫组合的新成员。时代相当于欧洲拉丁尼期(Ladinian Stagc)。     

江苏句容青山早三叠世鱼类

记述了在江苏句容东昌青山早三叠世下青龙组上部发现的鱼类,计有6属8种,其中4新属6新种,为属两目两科。属裂齿鱼目裂齿鱼科的有Perleidus piveteaui,Perleidus aff.P.madagascariensis.“Perleidus”eu-rylepidotrichia sp.nov.和Zhangina cylindrica gen.et sp.nov;属骨鱼目副半椎鱼科的有Stensionotus dongchangensis sp.nov.,Jurongia fusiformis gen.et sp.nov.,Qingshania cercida gen.et sp.nov.和Suius brevis gen.et sp.nov.。上列绝大部分属种的特征充分显示这个鱼群与马达加斯加北部早三叠世鱼群的亲密关系,少数属种的特征也反映其与东格陵兰早三叠世鱼群有某些关系。