浙江晚泥盆世西湖组的楔叶类化石

浙江晚泥盆世西湖组,以往发现的化石极少,主要是一些原始鳞木类化石.经李星学、陈其奭鉴定的化石名单有: Leptophloeum rhombicum Dawson, Sublepidodendron mirabile (Nath.), Eolepidodendron wusihense (Sze), 其次是可能属于楔叶类的 Hamatophyton verticillatum Gu et Zhi, 还有极少数分类位置不明的阔叶 Platyphyllum sp. 等.笔者于1984年6月至8月在萧山虎山的西湖组中采获了极其丰富、保存相当完整、外貌颇为奇特的大型楔叶     

晋北山西组具异型叶的“畸楔叶”组植物

Sphenophyllum Brongniart是晚古生代全球广布的植物,日本三叠纪卡尼期也有此类可疑标本发现(Asama et al.,1978,1980), Storch(1966)按叶形和脉序特征将该属分为三组,其中“畸楔叶”组植物以叶的面积较大,形态各异,叶脉外弯,部分直达顶端,部分交于侧边为共同特征。Batenburg(1981,1982)指出,除只有二歧分叉全裂线状叶的古老类型的种(如S.     

华南晚泥盆世假弱楔叶(Sphenophyllum pseudotenerrimum Sze)的新认识

假弱楔叶(Sphenophyllum pseudotenerrimum Sze)最早由斯行健于1936年依据江苏无锡上泥盆统五通组的标本建立,后续亦发现于其他产地如浙江、安徽等地区的晚泥盆世地层中。基于浙江长兴五通组的丰富化石,本文对假弱楔叶营养部分的形态学特征和个体发育进行了详细研究。该植物具有至少两级分枝,每级枝均具节与节间,表面具刺和纵肋。二级枝对生或单生于节部。叶轮生于节上,每轮可能有6枚叶,叶长6—18mm,3至4次等二歧式分叉,裂片为线形。发育早期阶段的二级枝节间极短,多轮叶子密集排布。对其分枝宽度与节间长度的统计分析表明,假弱楔叶的个体发育方式可能与石炭纪的楔叶属及现生木贼类相近,存在居间生长。随着植物的生长发育,居间分生组织的活动使得节间长度增加,其分枝长度也随之增长,而在此过程中,节间的数目不再增加或无明显增加。依据新材料,对假弱楔叶营养部分的形态进行了复原,认为植物体低矮,叶形稳定,可能不具异形叶性。     

新疆西准噶尔中泥盆世呼吉尔斯特植物群的特征、时代、古环境以及古植物地理学意义*

阐述呼吉尔斯特植物群的定义、分布、时代、组成和特点。呼吉尔斯特植物群主要代表我国北方区中泥盆世晚期的植物群,其具有全球广布型属种,也具有特化型植物。该植物群生物量巨大,发育小规模的森林,也形成了若干薄的煤层,成煤植物和森林冠层植物为石松类。结合该植物群化石埋藏学、沉积岩石学、煤岩学等研究,对呼吉尔斯特植物群的古环境以及古植物地理学意义进行探讨,提出:呼吉尔斯特组若干条保存有丰富植物化石和煤层的剖面,代表中泥盆世晚期区域性的陆相沉积环境,新疆西准噶尔在中泥盆世是重要的植物迁徙大陆桥。     

泥盆纪石松类研究新进展

简要论述了近十年来泥盆纪石松类研究取得的主要进展。分支系统学研究增进了对石松类起源与谱系分异的认识,新构建的系统发育树中石松纲与真叶植物互为姐妹群,并识别出原始鳞木目和异孢石松类两个单系。基于化石数据库和定量统计分析,揭示了泥盆纪石松类的多样性演变模式:早泥盆世布拉格期(Pragian)石松类的属种数量显著增加,在埃姆斯期(Emsian)至艾菲尔期(Eifelian)逐步取代工蕨类,至晚泥盆世进一步辐射。依据华南、新疆及全球其他地区丰富的化石材料,大量泥盆纪的石松植物新类群得以建立,一系列已有属种得到详细的再研究,明确了这些植物的生物学特征,也促进了对石松类根系、生长和繁殖习性演化的深入理解。对华南早泥盆世的镰蕨类和挪威中—晚泥盆世乔木状石松的研究分别揭示了这一时期植物-土壤相互作用及热带森林群落面貌,为了解早期维管植物对地球环境和陆地生态系统的影响提供了新的资料。     

江苏句容高骊山组植物化石

高骊山组的地质时代高骊山组的标准剖面在江苏句容县高资镇以南,东昌街以北的高骊山,本组名最早见于李四光,朱森(1932)的《南京龙潭地质指南》,但有关地层剖面的简略描述,在李毓尧等(1935,13页)的《宁镇山脉地质志》一书中才见到,内列有经高腾和斯行健(Gothan et Sze 1933)研究的植物化石     

浙江长兴晚泥盆世几种羽状复叶植物的发现及其意义北大核心CSCD

晚泥盆世是植物叶片形态复杂化进程中的一个重要时期,前裸子、种子、似真蕨和楔叶这四类植物都独立演化出了片化的大型叶。本文研究浙江长兴上泥盆统(法门阶)五通组的几种羽状复叶植物(3属4种),包括Sphenopteris(楔羊齿),Rhodea(须羊齿)和Triphyllopteris(三裂羊齿)。它们大多具二次羽状复叶,小羽片具有不同程度、数目和形状的裂片。这里明确Rhodea的晚泥盆世起源,并给出Triphyllopteris的最早化石记录。这些植物的分类尚不清楚,但为大型叶尤其是复叶的早期演化提供了新证据。     

浙江长兴晚泥盆世几种羽状复叶植物的发现及其意义

晚泥盆世是植物叶片形态复杂化进程中的一个重要时期,前裸子、种子、似真蕨和楔叶这四类植物都独立演化出了片化的大型叶。本文研究浙江长兴上泥盆统(法门阶)五通组的几种羽状复叶植物(3属4种),包括Sphenopteris(楔羊齿),Rhodea(须羊齿)和Triphyllopteris(三裂羊齿)。它们大多具二次羽状复叶,小羽片具有不同程度、数目和形状的裂片。这里明确Rhodea的晚泥盆世起源,并给出Triphyllopteris的最早化石记录。这些植物的分类尚不清楚,但为大型叶尤其是复叶的早期演化提供了新证据。     

山西保德晚石炭世至早二叠世重要孢粉属种丰度的变化及其反映的古生态变迁

山西保德扒楼沟剖面本溪组—太原组156块样品(本溪组47块、太原组75块和山西组34块)中,有113块产有保存良好的孢粉化石。结合现有原位孢粉的资料,通过大量的统计分析,作者在这段地层中识别出了植物群演替的四个阶段,从这四阶段开始地层层位的沉积构造判断,大致可以推断出这四次发展过程的主要诱发因素是在这段时间内频繁发生的海进,并且从孢粉丰度的变化中可以看出在这种动荡的环境下,同孢植物的真蕨类,以及楔叶类,由于在事件发生之后表现出较强的复苏能力,使得这段地层中的真蕨类以及楔叶类的孢子在整段沉积物中的含量相对较高,而石松纲的鳞木类以及松柏纲的科达类的复苏能力则相对较弱,因此产自这两类母体植物的孢粉在地层中始终不占主要位置。     

甘肃永昌乌拉尔世几种楔叶植物的发现及古地理意义

为了更好地了解晚古生代楔叶属的物种多样性及形态演化,通过对化石宏观形态的研究以及与相似化石种的对比,确定甘肃永昌太原组中几种楔叶植物化石的分类位置。本文共鉴定楔叶植物化石2属5种,其中包括营养叶和繁殖器官。基于这些楔叶属的新材料,对椭圆楔叶以及马齿楔叶的茎轴表面纵纹、叶片分裂次数等特征进行修订。同时报道楔叶穗属一新种Bowmanites yongchangensis sp. nov.。结合该属在晚古生代的古地理分布情况,表明在乌拉尔世早期该研究区内楔叶属植物呈现出较高的物种多样性,并推测该属植物的起源时间不晚于晚泥盆世法门期,在维宪期由华南地区传入华北地区后,于宾夕法尼亚亚纪晚期传入龙首山地区所在的阿拉善地块。     

On the origin of the Hirudinea and the demise of the Oligochaeta

The phylogenetic relationships of the Clitellata were investigated with a data set of published and new complete 18S rRNA gene sequences of 51 species representing 41 families. Sequences were aligned on the basis of a secondary structure model and analysed with maximum parsimony and maximum likelihood. In contrast to the latter method, parsimony did not recover the monophyly of Clitellata. However, a close scrutiny of the data suggested a spurious attraction between some polychaetes and clitellates. As a rule, molecular trees are closely aligned with morphology-based phylogenies. Acanthobdellida and Euhirudinea were reconciled in their traditional Hirudinea clade and were included in the Oligochaeta with the Branchiobdellida via the Lumbriculidae as a possible link between the two assemblages. While the 18S gene yielded a meaningful historical signal for determining relationships within clitellates, the exact position of Hirudinea and Branchiobdellida within oligochaetes remained unresolved. The lack of phylogenetic signal is interpreted as evidence for a rapid radiation of these taxa. The placement of Clitellata within the Polychaeta remained unresolved. The biological reality of polytomies within annelids is suggested and supports the hypothesis of an extremely ancient radiation of polychaetes and emergence of clitellates.     

On the ontogeny of the haptor and the evolution of the Monogenea

Data on the ontogeny of the posterior haptor of monogeneans were obtained from more than 150 publications and summarised. These data were plotted into diagrams showing evolutionary capacity levels based on the theory of a progressive evolution of marginal hooks, anchors and other attachment components of the posterior haptor in the Monogenea (Malmberg, 1986). 5 + 5 unhinged marginal hooks are assumed to be the most primitive monogenean haptoral condition. Thus the diagrams were founded on a 5 + 5 unhinged marginal hook evolutionary capacity level, and the evolutionary capacity levels of anchors and other haptoral attachement components were arranged according to haptoral ontogenetical sequences. In the final plotting diagram data on hosts, type of spermatozoa, oncomiracidial ciliation, sensilla pattern and protonephridial systems were also included. In this way a number of correlations were revealed. Thus, for example, the number of 5 + 5 marginal hooks correlates with the most primitive monogenean type of spermatozoon and with few sensillae, many ciliated cells and a simple protonephridial system in the oncomiracidium. On the basis of the reviewed data it is concluded that the ancient monogeneans with 5 + 5 unhinged marginal hooks were divided into two main lines, one retaining unhinged marginal hooks and the other evolving hinged marginal hooks. Both main lines have recent representatives at different marginal hook evolutionary capacity levels, i.e. monogeneans retaining a haptor with only marginal hooks. For the main line with hinged marginal hooks the name Articulon-choinea n. subclass is proposed. Members with 8 + 8 hinged marginal hooks only are here called Proanchorea n. superord. Monogeneans with unhinged marginal hooks only are here called Ananchorea n. superord. and three new families are erected for its recent members: Anonchohapteridae n. fam., Acolpentronidae n. fam. and Anacanthoridae n. fam. (with 7 + 7, 8 + 8 and 9 + 9 unhinged marginal hooks, respectively). Except for the families of Articulonchoinea (e.g. Acanthocotylidae, Gyrodactylidae, Tetraonchoididae) Bychowsky's (1957) division of the Monogenea into the Oligonchoinea and Polyonchoinea fits the proposed scheme, i.e. monogeneans with unhinged marginal hooks form one old group, the Oligonchoinea, which have 5 + 5 unhinged marginal hooks, and the other group form the Polyonchoinea, which (with the exception of the Hexabothriidae) has a greater number (7 + 7, 8 + 8 or 9 + 9) of unhinged marginal hooks. It is proposed that both these names, Oligonchoinea (sensu mihi) and Polyonchoinea (sensu mihi), will be retained on one side and Articulonchoinea placed on the other side, which reflects the early monogenean evolution. Except for the members of Ananchorea [Polyonchoinea], all members of the Oligonchoinea and Polyonchoinea have anchors, which imply that they are further evolved, i.e. have passed the 5 + 5 marginal hook evolutionary capacity level (Malmberg, 1986). There are two main types of anchors in the Monogenea: haptoral anchors, with anlages appearing in the haptor, and peduncular anchors, with anlages in the peduncle. There are two types of haptoral anchors: peripheral haptoral anchors, ontogenetically the oldest, and central haptoral anchors. Peduncular anchors, in turn, are ontogenetically younger than peripheral haptoral anchors. There may be two pairs of peduncular anchors: medial peduncular anchors, ontogentically the oldest, and lateral peduncular anchors. Only peduncular (not haptoral) anchors have anchor bars. Monogeneans with haptoral anchors are here called Mediohaptanchorea n. superord. and Laterohaptanchorea n. superord. or haptanchoreans. All oligonchoineans and the oldest polyonchoineans are haptanchoreans. Certain members of Calceostomatidae [Polyonchoinea] are the only monogeneans with both (peripheral) haptoral and peduncular anchors (one pair). These monogeneans are here called Mixanchorea n. superord. Polyonchoineans with peduncular anchors and unhinged marginal hooks are here called the Pedunculanchorea n. superord. The most primitive pedunculanchoreans have only one pair of peduncular anchors with an anchor bar, while the most advanced have both medial and lateral peduncular anchors; each pair having an anchor bar. Certain families of the Articulonchoinea, the Anchorea n. superord., also have peduncular anchors (parallel evolution): only one family, the Sundanonchidae n. fam., has both medial and lateral peduncular anchors, each anchor pair with an anchor bar. Evolutionary lines from different monogenean evolutionary capacity levels are discussed and a new system of classification for the Monogenea is proposed.In agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. EditorIn agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. Editor