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1.
Three Schizolepis species collected from the Lower Cretaceous layer of the Huolinhe Basin,Inner Mongolia,China are described.These fossils are Schizolepis longipetiolus Xu XH et Sun BN sp.nov.,which is a new species,Schizolepis cf.heilongjiangensis Zheng et Zhang,and Schizolepis neimengensis Deng.The new species is a well-preserved female cone,slender and cylindrical in shape.The seed–scale complexes have long petioles and are arranged on the cone axis loosely and helically.The seed scales are divided into two lobes from the base.Each lobe is semicircular or elongate ligulate in shape,widest at the middle or the lower middle part,with an obtuse or bluntly pointed apex.The inner margin is almost straight and the outer margin is strongly arched.On the surface of the lobe,there are longitudinal and somewhat radial striations from the base to the margin.The seed is borne on the adaxial surface at the base or middle of each lobe.Schizolepis was established in 1847,and,although more than twenty species have been discovered and reported,its phylogenetic position is controversial because of the imperfection of fossils.Most authors have considered there to be a close evolutionary relationship between Schizolepis and extant Pinaceae.Here,we analyze characteristics and compare Schizolepis with Picea crassifolia Kom,which is morphologically most similar to Schizolepis.The results indicate that the genus probably has a distant evolutionary relationship with extant Pinaceae.A detailed statistical analysis of the global paleogeographic distribution of Schizolepis showed that all the fossils of this genus appeared in strata ranging from the Upper Triassic to the Lower Cretaceous in the North Hemisphere,being rare in the Upper Triassic and Lower Jurassic,but being very common from the Middle Jurassic to the Lower Cretaceous,and particularly abundant in the Lower Cretaceous.According to the statistical results,we speculate that the genus originated in Europe in the Late Triassic then spread from Europe to Asia between the Late Triassic and the Late Jurassic.In the Early Cretaceous most species existed in China’s three northeastern Provinces and the Inner Mongolia Autonomous Region and adjacent areas.Combining the paleogeographic distribution of the genus with ancient climatic factors,we deduced that Schizolepis began to decline and became extinct in the Early Cretaceous,and the reason for its extinction is closely related to the icehouse climate during the Early Cretaceous.  相似文献   

2.
Well-preserved Ginkgo pollen organs are analyzed from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, and are described as a new species, Ginkgo hamiensis Z.X. Wang et B.N. Sun sp. nov. The immature male cones are cylindrical and catkin-like, with two longitudinal stripes on the stalk. The pollen sacs are shaped like a long oval with two pollen sacs fused together for each microsporophyll, and the microsporophyll tip is a triangular cystidium. The pollen grains are oblong or fusiform and monocolpate; both ends are blunt or sharp. By comparison with previously reported fossil records of Ginkgo plants, we determined that the current fossils are different from all other reported species; thus, the present fossil is referred to as a new species of Ginkgo. The reproductive organs of the Ginkgo fossils described herein can provide valuable information for the study of Ginkgo plants. Further, there are two probable evolutionary trends in the Ginkgo pollen cones. One trend is that the number of pollen sacs changed from three or four during the Jurassic and Cretaceous to two at the present day; the other is that the number of pollen sacs has remained two from the Middle Jurassic to the present day. In addition, the pollen cones described herein are similar to the pollen cones of the extant Ginkgo, which strongly indicates that the morphology of Ginkgo plants may have remained highly conserved over millions of years.  相似文献   

3.
现已绝灭的古老松柏类植物似纵属Elatides在中生代北半球中高纬度植被组成研究上具有重要意义。甘肃酒西盆地早白垩世地层中发现了Elatides的营养枝和雌球果,并保存有较好的碳膜,对它们进行了详细的宏观形态和微细特征研究。根据营养枝、叶角质层、花粉、球果、苞鳞和种子的特征,鉴定这些化石为2个种:Elatides harrisii Chow和Elatides curvifolia (Dunker) Nathorst。其中:Elatides harrisii的突出特征是,花粉球形且具乳状小突起、表面光滑无纹饰,侧面观具褶皱;Elatides Curvifolia的显著特点为,着生于苞鳞腹面基部的种鳞先端三裂,具三枚胚珠。这些特征与现生杉木Cunninghamia非常相似,推论Elatides与现生Cunninghamia可能具有亲缘关系。通过对Elatides地质历史和地理分布的研究,发现该属的演化方向与中生代大陆漂移的方向具可比性,因而为板块构造学说提供了又一古生物学佐证。  相似文献   

4.
福建永安下白垩统坂头组Elatides属雌球果化石 研究   总被引:1,自引:0,他引:1       下载免费PDF全文
对采自福建永安市下白垩统坂头组的似纵属Elatides雌球果化石进行了宏观形态和角质层特征的研究,这些球果均单独保存,较小,果鳞较多,螺旋状紧密排列,顶端收缩呈尖刺状,与Elatides的特征相符。根据球果的形态、果鳞及其球果中轴的特征,将这些球果鉴定为3个种,即永安似纵(新种)Elatides yonganensis Dai et Sun, sp. nov.、弯叶似纵(相似种)Elatides cf. curvifolius及一未定种Elatides sp.。其中重点描述了新种E. yonganensis的形态特征,该球果以中轴呈波状,果鳞顶端较长、较尖,腹面具有锯齿状的膜质小舌,每一果鳞具有大概5枚种子而区别于以前报道的任一已知种。同时对中国的Elatides化石记录进行了收集整理,Elatides属的球果化石在福建永安坂头组的发现表明其分布区可达25°N,丰富了该属植物的化石记录并扩大了其分布范围。  相似文献   

5.
Modern gnetophytes consist of three families, i.e. the Ephedraceae, the Gnetaceae, and the Welwitschiaceae, which show diversified morphology. The basal group Ephedraceae possesses an extremely reduced female cone with only the uppermost pair/whorl being fertile, while both the Gnetaceae and the Welwitschiaceae bear female cones/spikes with multiple whorls of fertile bracts. Here, we describe a new ephedroid macrofossil, Liaoningia decussata Yang et Lin, gen. et sp. nov., from the Lower Cretaceous Yixian Formation of western Liaoning in China. This species has typical ephedroid morphology, e.g. the dichasial branching shoot system, swollen nodes, internodes having many fine longitudinal striations, and decussate phyllotaxy, lengthy linear leaves possessing two parallel veins, and female cones consisting of paired bracts. This new genus is similar to the Ephedraceae in its vegetative organs, but differs from the latter by the female spikes with multiple pairs of fertile bracts. In this respect Liaoningia is similar to both the Gnetaceae and the Welwitschiaceae, but distinctly differs from the latter two genera in its vegetative organs. As a result, our new genus shows intermediate morphology between the Ephedaceae and the other two families of the gnetophytes, and is probably a missing link in the evolutionary process from the Ephedraceae to the clade including the Gnetaceae and the Welwitschiaceae.  相似文献   

6.
A sequence of Triassic rocks is exposed near the town of Concepción, Chile. These clastic strata are interpreted as the deposits of rivers, lakes, playas, and alluvial fans. The deposits comprise conglomerates, arkosic sandstones, and sand-, silt- and mudstones. Four facies associations comprising eight sedimentary facies can be distinguished. Plant fossils from the sedimentary sequence of the Santa Juana Formation indicate a Carnian age. The flora includes ferns (Gleichenites, Cladophlebis, Dictyophyllum, Thaumatopteris, Asterotheca, Saportaea) and seed ferns (Kurtziana, Antevsia, Dicroidium), ginkgophytes (Sphenobaiera), cycads (Pseudoctenis), conifers (Heidiphyllum, Telemachus, Rissikia), and gymnosperms of uncertain affinities (Linguifolium, Gontriglossa). Two new species are presented: Pseudoctenis santajuanensis and Gontriglossa reinerae.  相似文献   

7.
袁丽平  解三平  孙宇  刘志伟  陈杰  郭虎 《地质通报》2017,36(8):1334-1342
云南现代真蕨类植物资源丰富,蕨类植物多样性的地史起源,必须从化石记录入手。在云南临沧上中新统邦卖组植物化石采集中发现了槲蕨属1块不育叶和2块腐殖叶的新材料,这些标本为修订Drynaria propinqua Wen et al.,2013,以及揭示该种不育叶和腐殖叶的特征提供了新的材料。通过与槲蕨属国内外报道的化石种和现生种的详细比较,将其重新定名为Drynaria cf.propinqua。Drynaria cf.propinqua的发现,表明云南临沧晚中新世的气候与现今中国西南地区温暖湿润的气候类似,这些附生植物的生活习性表明,临沧地区复杂分层的森林生态系统至少在晚中新世已经确立。  相似文献   

8.
The new genus Krassilovidendron Sokolova, Gordenko et Zavialova with the type species Krassilovidendron fecundum Sokolova, Gordenko et Zavialova is described on the basis of numerous compressions of polymorphic shoots in organic connection with seed and pollen cones from the Albian–Cenomanian of the Kubaevo locality (Russian Federation, Kemerovo region, Western Siberia). The new taxon is characterized by an assemblage of features that distinguishes it from all known extant and fossil conifer genera: shoots with helically arranged leaves varying from amphistomatic small scale-like leaves to strictly epistomatic linear-lanceolate leaves; terminal, ellipsoidal to obovate seed cones, bearing 14–26 helically arranged peltate bract-scale complexes (bract and ovuliferous scale are completely fused) with a cylindrical vascular bundle, bifurcating into abaxial and adaxial dichotomizing bundles; up to 22 inverted seeds of various shapes with a protruding micropyle and inconspicuous lateral wings, which are arranged in two to five arcuate rows; solitary terminal pollen cones with helically arranged microsporophylls, each bearing four abaxial microsporangia; and small pollen grains with a relatively short papilla, numerous orbicules on the surface, and a three-layered ectexine with a tectum of strongly fused granules, an infratectum of smaller and more loosely arranged granules, and a thin footlayer. The new taxon possesses a combination of characters indicating it belongs to the subfamily Sequoioideae. Krassilovidendron shares the greatest number of features with Sequoia Endlicher and Sequoiadendron Buchholz, and fewer characters with Metasequoia Miki ex Hu et W.C. Cheng.  相似文献   

9.
Pollen, plant macrofossil, and radiocarbon-dating studies of seven exposures of fluvial sediments in the Tunica Hills region of southeastern Louisiana and southwestern Mississippi provide new information on late Wisconsinan vegetation, flora, and environment of the region. The assemblages date between 25,250 and 17,530 yr B.P. Pollen and macrofossil assemblages are dominated by Picea, which comprises 40-70% of the pollen assemblages. Abies and Larix pollen and macrofossils are absent, in contrast to sites to the north in the central Mississippi Valley. Deciduous hardwoods (Quercus, Fagus, Fraxinus, Carya, Juglans nigra, Acer, Ulmus) are minor components of both pollen and macrofossil assemblages. Radiocarbon dates of Picea and Quercus wood indicate that these two genera grew contemporaneously in the region. Regional upland forests were dominated by Picea. Picea cones and cone fragments are not typical of any extant North American species, and probably represent either an extinct species or an extinct variety or subspecies of Picea glauca. Late Wisconsinan climate of the region was cooler than present, but not necessarily as cool as implied by P. glauca or other "boreal" taxa.  相似文献   

10.
A new species of Araucaria, Araucaria beipiaoensis sp. nov., collected from the Middle Jurassic Tiaojishan Formation, southern hill of Shebudai village, near Beipiao city, western Liaoning is based on a permineralized female cone, which is ovate to elliptical in shape, about 11 cm × 7 cm × 4.5 cm in size. The cone bears rhomboid bracts that are spirally attached, texture thicker, with wings on both sides, with a detached lamina-like apex at the tip. In inner structure the ovuliferous scales are thicker and fused with bracts at the end with a ligular sulcns. There is one wingless ovule/seed per seed-scale complex embedded in the ovuliferous scale tissue, with the micropyle directed toward the cone axis. The ovules/seeds are long ovate or elliptical in shape, 1 cm long and near the base about 3 mm in diameter; the ovule/seed integuments have begun differentiation into 3 layers: the sarcotesta, sclerotesta, and endotesta. The nucellus is free from the enclosing integuments except in the chalazal region where it is fused to the inner layer (endotesta) of integument. Some ovules show cellularized nucellar tissue. Mature seeds exhibit the papery-thin wavy nucellus characteristically near to the micropyle. The embryonic tissue appears to be four cotyledons. The morphology and structure of the cone shows a close relationship to the araucarian cones of fossil and living genera but differs from any known species. The new species is distributed in the Middle Jurassic of the northern hemisphere, especially Asia, and has important significance for the evolution of the Family Araucariaceae.  相似文献   

11.
A new genus and species, Rebouliothallus huolinhensis sp. nov., and two uncertain species, Ricciopsis sp. and Hepaticites sp., are described. The fossils were collected from the Lower Cretaceous Huolinhe Formation of Huolinhe Basin, northeastern China. The new genus Rebouliothallus was established in the Aytoniaceae family of Marchantiales. Rebouliothallus huolinhensis appears to be quite similar to species of the extant genus Reboulia Raddi. The species is characterized by the relatively large ventral scales. Ventral scales are large, imbricate and arranged in two rows on the ventral surface. Rhizoids are either pegged or smooth. Ricciopsis sp. is characterized by the rosette-forming thallus. Hepaticites sp. shows some similarities to liverworts. Of the forty-nine Early Cretaceous floras of China, only two floras, one from the Huolinhe basin, Inner Mongolia and the other from the Jixi Basin, Heilongjiang Province, contain fossil liverworts. The rare fossil liverwort records in the Early Cretaceous floras of China may be the result of taphonomic bias.  相似文献   

12.
The Mission Paléoanthropologique Franco-Tchadienne (MPFT) found a new species of Orycteropodidae (Mammalia, Tubulidentata) in the Kollé fossiliferous sector, northern Chad. After Orycteropus abundulafus [Journal of Vertebrate Paleontology 20 (1) (2000) 205–209; Lehmann, T., Vignaud, P., Likius A., Brunet M., in press. A new Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of Northern Chad. Zool. J. Linnean Soc.], this specimen is the second complete skeleton of fossil aardvark found in the Djurab desert. It is the first complete representative of an Orycteropus species found in the Pliocene of Africa. In regard to the Miocene fossil aardvarks, this new taxon, Orycteropus djourabensis nov. sp., shows more affinities with the extant O. afer. The main differences are the larger teeth and the shorter hand in the fossil form. Kossom Bougoudi and Kollé represent a chronological series that gives a unique opportunity for studying the evolution of the African Tubulidentata around the Mio-Pliocene boundary (5.5-4 My). The new species is distinct from the older Chadian Orycteropodid from KB and it embodies the taxonomic turnover that took place within the order Tubulidentata around this boundary in Africa. Moreover, this new species is the oldest known Orycteropus species that clearly belongs to the modern forms including the extant aardvark.  相似文献   

13.
Schizolepis daohugouensis sp. nov. is described from the Jurassic sediments of Daohugou flora, from Ningcheng County, Inner Mongolia Autonomous Region, China. The female cone is slender, cylindrical in shape, seed scale complexes are loosely and helically arranged on the cone axis at intervals of 3–5 mm. The seed scales are bilobed and divided almost from the base; the scales have no evident petiole but an articulation at the region of attachment to the cone axis. Each lobe of the seed scales is oval in shape, widest at the lower middle part; lobes are obtusely pointed with entire margins. Bract scale is fan shaped. Based on the records of Schizolepis, this is the first report of the occurrence of female cone of Schizolepis with the seed scales, the winged seeds and vegetative branches preserved together in the Jurassic deposits. The new discovery provides evidence that confirms the phylogenetic position of Schizolepis to the extant Pinaceae.  相似文献   

14.
在内蒙古固阳县以东下湿壕地区 1∶5万区域地质调查中 ,首次在前人划分的下白垩统固阳组 采到瓣腮类、腹足类、介形类、轮藻、植物等大量化石。结合地层沉积组合特征 ,将原固阳组重新厘定为下白垩统李三沟组。这一地层层位的厘定和古生物化石的发现 ,对进一步探讨固阳盆地的构造演化和成煤规律等都将具有重要的理论意义和实际价值  相似文献   

15.
Climate change during the Quaternary played an important role in the distribution of extant plants. Herein, cone scales of Cedrus (Pinaceae) were uncovered from the Upper Pliocene Sanying Formation, Longmen Village, Yongping County of Yunnan Province in southwestern China. Detailed comparisons show that these fossils all belong to the genus Cedrus (Pinaceae), and a new species is proposed, Cedrus angusta sp. nov. This find expands the known distribution of Cedrus during the Late Pliocene to Yunnan, where the genus no longer exists in natural forests. Based on the analysis of reconstructed Neogene climate data, we suggest that the intensification of the East Asian winter monsoon during the Quaternary may have dramatically increased seasonality and given rise to a much drier winter in Yunnan. Combined with information on Cedrus fossil records and its seed physiology, we conclude that the intensification of a drier climate after the Late Pliocene may have prevented the survival of Cedrus seedlings, leading to the eventual disappearance of Cedrus in western Yunnan. This study indicates that the topography in southwestern China acted as a vital refuge for many plants during the Quaternary, but that other species gradually disappeared due to the intensification of the monsoonal climate.  相似文献   

16.
Bennike, O., Knudsen, K. L., Abrahamsen, N., Böcher, J., Cremer, H. & Wagner, B. 2010: Early Pleistocene sediments on Store Koldewey, northeast Greenland. Boreas, Vol. 39, pp. 603–619. 10.1111/j.1502‐3885.2010.00147.x. ISSN 0300‐9483. Marine Quaternary deposits, here named the Store Koldewey Formation, are found at ~120 m above sea level in northeast Greenland (76°N). The sequence is referred to the Olduvai normal polarity subchron at 1.95–1.78 Ma BP based on palaeomagnetic studies (palaeomagnetically reversed), amino acid epimerization ratios and evidence from marine and non‐marine fossils. The sediments and the fauna show that the sequence was deposited on a mid or inner shelf, and some elements of the marine mollusc and foraminiferal assemblages indicate water temperatures between ?1 and +1 °C and seasonal sea ice cover during deposition. Mean summer air temperatures were around 6 °C higher than at present, as demonstrated by the occurrence of southern extralimital terrestrial species. Well‐preserved remains of land plants indicate that the adjacent land area was dominated by sub‐arctic forest‐tundra with the trees Larix and Betula, shrubs, herbs and mosses. Most of the species represented as fossils have recent circumpolar geographical ranges. An extinct brachiopod species and an extinct gastropod species have been found, but the other macrofossils are referred to extant species. The brachiopod is erected as a new genus and species, Laugekochiana groenlandica. Correlation of the Koldewey Formation with the Île de France Formation farther to the north is suggested. Member A of the Kap København Formation in North Greenland is referred to the Late Pliocene, whereas Member B of the Kap København Formation is suggested to be slightly older than the Store Koldewey Formation.  相似文献   

17.
We describe a large collection of fossil ‘waterfowl’ bones that are referable to the extinct clade Presbyornithidae (Anseriformes). All of these fossils were collected between 1971 and 1994 from Upper Paleocene and Lower Eocene sediments at the Tsagaan Khushuu site in the Gobi Desert of southern Mongolia. The collection includes specimens referred to a new small species within the genus Presbyornis Wetmore, 1926 as well as large numbers of bones that we place in the genus Presbyornis. On this basis of the Tsagaan Khushuu collection we suggest that several species of Presbyornis likely coexisted in this region; indeed, the presence of large numbers of middle‐sized, morphologically consistent but probably ecologically disparate species at the Tsagaan Khushuu site is consistent with the range of variation seen, for example, in taxa of extant dabbling ducks (Anatini). Although the anatomy and phylogenetic position of Presbyornithidae (in particular Presbyornis) are well known, this material from Mongolia further demonstrates the prevalence of these birds in aquatic and semi‐aquatic habitats by the earliest Paleogene. Because presbyornithids are also well documented from the late Cretaceous, their palaeoecology and morphological diversity provides a clue to selective avian survivorship across the Cretaceous‐Paleogene (K‐Pg) boundary. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

18.
Precambrian microbial fossils show carbonaceous cellular structure, which often resemble in shape and size cyanobacteria and other prokaryotes. Morphological taxonomy of these minute, simple, and more or less degraded fossils is, however, often not enough to determine their precise phylogenetic positions. Here we report the results of micro-FTIR spectroscopic analyses of well-preserved microfossils in 850 Ma and 1900 Ma stromatolites, together with those of 8 species of extant prokaryotes and 5 of eukaryotes for comparison. These Proterozoic fossils have low CH3/CH2 absorbance ratios (R3/2 < 0.5) of aliphatic CH moieties, suggesting selective preservation of long, straight, aliphatic carbon chains probably derived from bacterial membrane lipids. All the observed R3/2 values of coccoids, filaments and amorphous organic matter resemble lipid fractions of extant Bacteria including cyanobacteria, but not Archaea. The results indicate that Proterozoic microfossils belong to Bacteria, which is consistent with the cyanobacterial origin inferred from morphology. Moreover, the R3/2 value of fossilized cell would reflect chemical composition of its precursor membrane lipid, thus could be a useful new tracer for distinguishing Archaea, Bacteria and possibly Eucarya for fossilized and extant microorganisms.  相似文献   

19.
<正>A new fossil chironomid,Tanytarsus serafini,found in Baltic amber is described and illustrated based on adult males.The new species and similar extant species of the genus Tanytarsus van der Wulp are compared. Due to several distinct characters of wing,legs and hypopygium,a new species group for Tanytarsus serafini is proposed,and its diagnostic features are evaluated.  相似文献   

20.
Halkieria is an Early Cambrian fossil genus with proposed phylogenetic affinities ranging from stem group lophotrochozoan to stem-group aculiferan. Skeletal similarities are often cited as evidence in support of a mollusk interpretation for Halkieria and related Cambrian fossils. The skeletal microstructures of the polyplacophoran mollusk (chiton) Ischnochiton hakodadensis, which bears perinotum elements resembling sclerites of halkieriids and other coeloscleritophoran small shelly fossils (SSFs), were studied to evaluate the interpretations. There are both similarities and differences between chiton skeletal structures and halkieriid sclerites: 1) the head valve of L hakodadensis and the dorsal shell of Halkieria evangelista share a similar pattern of fine concentric growth lines, but halkieriid dorsal shells lack other polyplacophoran valve characteristics, including V-shaped indentation, radiate ribs; 2) the arrangement of I. hakodadensis perinotum elements in three zones is somewhat similar to the arrangement pattern of halkieriid sclerites; 3) the inner perinotum scales of L hakodadensis (-200 μm in diameter) have a base and a blade, remarkably similar in morphology to halkieriid palmate sclerites (-400 μm in diameter). However, I. hakodadensis perinotum scales are nearly solid whereas halkieriid sclerites are hollow. These observations add a microstructural dimension to the skeletal comparison between mollusks and halkeriids, and may prove to be useful in resolving the phylogenetic affinity of Halkieria and the Halwaxiidae.  相似文献   

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