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1.
东濮地区晚始新世沙河段组四段上部至三段轮藻植物群生存于含钙量高的咸化型水体中,它们的横向分布反映了湖盆中部存在着一个NNE向的隆起地带。早渐新世沙河街组二段轮藻植物群生长于含钙量低的淡水水体中,它们的横向分布反映了湖盆中部古地形自南向北高低相间。晚渐新世东营组轮藻植物群生存于含钙量低的淡水水体中,它们的横向分布反映了湖盆的古地势较为平坦。  相似文献   

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The Juglandaceae (walnut family) has an excellent fossil record of various organs extending back to the earliest Tertiary. Several genera which today are restricted to isolated geographic regions were widespread in the Northern Hemisphere during the Tertiary. This paper focuses upon the fossil record of the Pterocarya alliance of the subfamily Juglandoideae, tribe Juglandeae. The Pterocarya alliance includes only two modern genera, Pterocarya (five species) and Cyclocarya (one species), both restricted to Eurasia. Paleogene sediments of the Rocky Mountain Region have yielded three genera and four species referable to the Pterocarya alliance: Cyclocarya (two species), Pterocarya, and a new genus, Polyptera. Although three of the four Paleogene species described here are attributed to present day genera, each represents an extinct form, which cannot be accommodated by any single living species. These fossils, reviewed with other published reports, indicate that the Pterocarya alliance, like the Engelhardia alliance of the same family, was more diverse and much more widespread geographically in the Tertiary than it is today.  相似文献   

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淮南地区新元古代九里桥组主要由砂质和泥质灰岩、叠层石灰岩以及白云质灰岩组成,含有著名的“淮南生物群”的重要分子。研究采用浸解法在该组碳酸盐岩中发现了大量的疑源类化石,它们以球形亚类为主,在组合面貌上继承了其下伏刘老碑组的疑源类组合特征。但化石个体较大,多细胞植物碎片含量明显增加,化石在不同层位的分布不均匀是九里桥组疑源类组合的显著特征。另外在该组中还发现了一些新的疑源类化石如:Bailikania diligena,?Lomentunella vagtinata Hermann。文中还对九里桥组的凝源类组合与宏体化石、叠层石礁体的发育之间的关系等进行了探讨。  相似文献   

5.
邓占球 《古生物学报》2001,40(2):219-223
对床板珊瑚化石群的分析表明,南天山阿尔皮什表布拉克组的地质时代为早泥盆世早期,所含珊瑚群与滇西北,西秦岭,内蒙古达尔罕茂明安联合旗,吉林二道沟的珊瑚群面貌相似,明确属于古特提斯生物地理区内,而与北天山,淮噶尔,北山,大,小兴安岭等地区同期地层所产者存在明显差异。  相似文献   

6.
新疆巴楚中奥陶统上部一间房组瓶筐石礁丘的演化意义   总被引:8,自引:1,他引:7  
从建造时代和群落组成的角度,专论新疆巴楚地区一间房组瓶筐石礁丘的演化定位。瓶筐石作为群落的主体造礁始于早奥陶世早期,繁盛于早奥陶世晚期,中奥陶世开始趋于衰落。一间房组发育中小型点礁丘,除礁灰岩中常见的藻屑外,主要由瓶筐石并伴生少量石海绵共同形成礁格架岩。在群落组成上,一间房组的瓶筐礁丘与世界其它地区的瓶筐礁类似,但在建造时间上却显得极为特殊:中奥陶世晚期。这时,一个全新的群落——珊瑚—层孔海绵礁群落开始在世界其它地区起源,却全然不见于一间房组。一间房组的礁丘在时间上完全不吻合于早奥陶世的瓶筐石造礁事件,而是晚于此类礁繁盛期并滞后了约10Ma,是目前所发现这类礁群落在全球范围内的孓遗孤例,是承先而不启后的礁群落。  相似文献   

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This report is based on nine specimens of fossil conifer stems and leaves from the Early Oligocene Jansen Creek Member of the Makah Formation. They were collected along the northern shore of the Olympic Peninsula of Washington. The fossils are preserved as siliceous permineralizations and were exposed in surface view along rock fractures. Details of leaf morphology and epidermal construction appear on fracture surfaces of certain specimens while the cellular construction of the leaves and twigs is visible in thin sections. Leaves are dorsiventrally flattened, attached to twigs that contain up to four growth increments of secondary xylem, up to 2.3 cm long, 3.5 mm wide, and have parallel margins with minute teeth. The leaves are about 0.5 mm thick and have a central vascular strand surrounded by transfusion tissue. A large resin canal occurs abaxial to the vascular strand, and generally two additional resin canals occur in the mesophyll near each leaf margin. Leaves are mostly hypostomatic, with sunken stomata in two longitudinal bands, one to each side of the midline of the leaf and each containing eight to 13 longitudinal rows of stomata. Several unusual anatomical features in the stems also occur in the peduncle and cone axis of seed cones described as Cunninghamiostrobus goedertii, which occurs at the same locality. Thus, the leafy twigs belong to the same species as produced the cones. The cones, leaves, and shoots of this Tertiary conifer are similar to those of modern Cunninghamia but differ from the living species in several respects.  相似文献   

8.
Fruits, catkins, and associated leaves of at least two extinct trigonobalanoid taxa have been discovered at an Oligocene fossil plant locality rich in fagaceous remains. These fossils exhibit a mosaic of fruit and pollen characters found in the two extant subfamilies Castaneoideae and Fagoideae of Fagaceae. Comparison with cladograms based on modern taxa suggests that these extinct taxa were similar to the ancestors of subfamily Fagoideae and may have been intermediate between Fagus and the modern trigonobalanoid genera. Pollen types isolated from the fossil staminate catkins provide unique character states that are transitional between modern pollen types in Fagaceae and are important in understanding the evolution of exine micromorphology within the family. This analysis provides a striking example of the use of character data from fossils to determine character-state adjacency prior to polarization of characters using outgroup comparison. Because of the mosaic nature of their character complexes, these fossils support monophyly in both the family Fagaceae and the subfamily Fagoideae. In addition, the occurrence of trigonobalanoid fossils in the Oligocene of North America has interesting biogeographic implications and provides insights into the nature of North American Fagaceae during the Tertiary.  相似文献   

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徐州王庄煤矿山西组孢粉植物群及其地层意义   总被引:1,自引:0,他引:1  
徐州王庄煤矿山西组中、下部产有丰富的孢粉化石,保存完好,共计55属132种(包括3新种)2个未定型孢子及1个疑源类未定类型。根据孢粉属种组成及其含量的变化,自下而上分为两套组合:Cyclogranisporites-Gulisporites-Laevigatosporites-Florinites组合(简称组合1)和Calamospora-Gulisporites-Vesiculatisporites-Florinites组合(简称组合2)。根据组合内一些重要分子的地质时限讨论及其与相关组合的对比,将组合1的地质时代归为早二叠世早期,组合2的时代归为早二叠世晚期。文中描述孢子3新种,图示孢子花粉91种。  相似文献   

10.
略阳组分布于南秦岭勉略缝合带附近,是略阳地区重要的岩石地层单元。本次研究在略阳灵岩寺南部剖面的略阳组获得牙形刺13枚,共识别出3属5种,包含2亚种和2未定种,分别为:Siphonodella homosimplex,Polygnathus communis communis,Po.inornatus inornatus,Po. sp.和Pseudopolygnathus sp.。该牙形刺组合可以与华南同时期牙形刺进行对比,时代为早石炭世杜内期早期,这为确定略阳组的下部层位的具体时代提供了新的牙形刺证据。略阳组中所产出的Si.homosimplex为华南地区浅水相牙形刺的典型代表,Po.inornatus inornatus广泛见于西欧的浅水相地层,这表明在早石炭世期间勉略地区为浅水碳酸盐岩台地沉积环境,且与华南地区生物区系存在紧密联系,同前人根据底栖生物化石研究得出的结论相一致。  相似文献   

11.
作者系统地研究了海南乐东洪帽剖面鹿母湾组孢粉化石,共计26属60种,其中苔藓类植物孢子1属3种,蕨类植物孢子18属30种,裸子植物花粉7属27种,组成以Cicatricosisporites-Schizaeois porites-Ephedripites-Exe-sipollenites为特征的孢粉组合.依据组合中主要分子和重要分子地质时限的讨论以及与相关孢粉组合进行比较,将洪帽剖面鹿母湾组的地质时代归为Aptian期-早Albian期.  相似文献   

12.
本文描述和讨论广东连阳地区谷田组地层的化石共14属18种,即:Paracalamites sp.,Annularia pingloensis(Sze)Gu er Zhi、Lobatannularia cathaysiana Yao、L.multifoliaKon'on et Asama、L.sp.、Schizonerua wangtangiana sp.nov.、Pecopteris hemitelioidesBrongn.、P.valida sp.nov.、Cladophlebis varia sp.nov.、Danaeites guangdongensis sp.nov.、Ptychocarpus unauriculatus sp.nov.、Odontopteris plicatoides sp.nov.、Neuropteri-diopsis longovata gen.et sp.nov.、Compsopteris contracta Gu et Zhi、Gigantonoclea cra-ssa sp.nov.、Gigantopterts?nicotianaefolia Schenk、G.parvipinnulata sp.nov.和 Rhipido-psis sp.等,其中有1新属、9新种和2未定种。谷田组顶部发现了早二叠世晚期的(竹蜓)类层,下段则与下伏的茅口组假整合。植物群的地质时代为早二叠世晚期。  相似文献   

13.
星叶草属2隙节及2裂叶及其系统学意义   总被引:1,自引:0,他引:1  
报道了存在于星叶草属植物中与单隙节共存的2隙节及与不分裂叶共存的2裂叶。通过分析后认为,这两个现象在该属植物中的出现并不是异常的。  相似文献   

14.
Compressed mimosoid inflorescences from a Paleocene-Eocene boundary locality in western Tennessee are the earliest fossil evidence of the subfamily. The discovery confirms the antiquity of a suite of characters that has been considered primitive based on the comparative morphology of modern mimosoids. The fossil characters are also consistent with the suggested close relationship (ancestral or sister group) between the subfamily Mimosoideae and the Dimorphandra group of the tribe Caesalpinieae (subfamily Caesalpinioideae). These flowers show little change in morphology or size in the basal to Upper Eocene interval.  相似文献   

15.
16种高山植物叶片内的异细胞及其生态学意义   总被引:18,自引:5,他引:13  
报道了16种高山植物叶片内异细胞的分布和特征,其中8种植物叶肉的栅栏组织靠近上表皮的一层或两层细胞为民细胞,有些种的海绵组织中含有异细胞;有此种的上表皮中含有异细胞。另外绝大多数的植物的维管组织之中有异细胞存在。  相似文献   

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1992年,中国科学院古脊椎动物与古人类研究所从人民来信中得知,在山西永和县桑壁镇附近的河沟中发现了陆生四足动物化石。不久古脊椎所的专业人员就到化石产地进行了实地调查,并发掘出了几具保存较好的爬行动物化石。化石保存在坚硬的细砂岩中,已经修理出其中一个头骨(如图1所示)。经初步鉴定,这批化石是一类初龙形类动物,与产自新疆吐鲁番盆地中三叠世克拉玛依组的达板吐鲁番鳄(Turfanosuchusdabanensis)(Youns,1973)关系较近,但是其内颈动脉孔位于基蝶骨侧面,而不是位于腹面,这表明…  相似文献   

18.
钙质超微化石楔石属的三个分子:Sphenolithus predistentus,Sphenolithus distentus,Sphenolithus ciperoensis是渐新世生物地层重要的化石带标志分子。这三个物种属于该属渐新世的一个演化序列,该演化序列早期的S.predistentus-S.distentus和晚期的S.distentus-S.ciperoensis两对物种之间存在形态过渡类型,使得难以准确鉴定,导致渐新世生物地层划分一些问题。此外,对这三个物种演化的关系是渐进式或是间断平衡式也有不同看法。为进一步了解这三个物种形态演化特征并探讨它们的演化关系,我们选择南海北部ODP 1148站位及IODP U1435站位的渐新世沉积物样品,针对这三个物种个体的形态特征展开定量形态研究。使用奥林巴斯光学显微镜对两个站位19个样品里1 171个楔石个体进行六个形态参数度量,包括了个体总高、顶刺高、基座高、基座宽、基座夹角及消光线夹角。统计结果显示,S.predistentus-S.distentus-S.ciperoensis演化序列中,这三个种的六个形态学参数变化范围边缘相互叠复,缺乏可确切划分界限。三个种个体基座高与基座宽之比依三者的演化次序呈现逐渐增大的渐变关系。以上证据表明S.predistentus-S.distentus-S.ciperoensis为渐进式演化。  相似文献   

19.
The gametophytic chromosome number for the giant senecios (Asteraceae, Senecioneae, Dendrosenecio) is n = 50, and for the giant lobelias (Lobeliaceae, Lobelia subgenus Tupa section Rhynchopetalum) it is n = 14. Previous sporophytic counts are generally verified, but earlier reports for the giant senecios of 2n = 20 and ca. 80, the bases for claims of intraspecific polyploidy, are unsubstantiated. The 14 new counts for the giant senecios and the ten new counts for the giant lobelias are the first gametophytic records for these plants and include the first reports for six and four taxa, respectively, for the two groups. Only five of the 11 species of giant senecio and three of the 21 species of giant lobelia from eastern Africa remain uncounted. Although both groups are polyploid, the former presumably decaploid and the latter more certainly tetraploid, their adaptive radiations involved no further change in chromosome number. The cytological uniformity within each group, while providing circumstantial evidence of monophyly and simplifying interpretations of cladistic analyses, provides neither positive nor negative support for a possible role of polyploidy in evolving the giant-rosette growth-form.  相似文献   

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Specimens showing staminate and pistillate inflorescences attached to branches bearing Fagopsis longifolia (Lesq.) Hollick foliage, from the Oligocene Florissant flora of Colorado, permit a relatively complete characterization of the extinct Fagopsis plant. The alternately arranged simple leaves have pinnate craspedodromous venation and prominent simple teeth. Staminate inflorescences are globose on a stout peduncle and contain anthers with tricolporate pollen. Pistillate inflorescences are ovoid heads with compact, helically arranged three-flower units and are interpreted to have three styles per flower. The infructescence consists of small wedge-shaped cupules, each containing three tiny fruits, and subtended by a persistent bract. The cupules unravel from the swollen peduncle at maturity and are often dispersed as strings of adhering fruit-wedges which frequently take on a regular, more or less circular appearance. Fagopsis is unlike any living genus but has characters which support a relationship to the Fagaceae. Unlike extant members of the family, which typically have fruits adapted for animal dispersal, Fagopsis is less obviously specialized and perhaps adapted for wind dispersal. The striking differences in fruiting structures between Fagopsis and extant Fagaceae parallel the differences between the extant genera Platycarya and Juglans in the Juglandaceae, and Alnus and Corylus in the Betulaceae.  相似文献   

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