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1.
A New Angiosperm Genus from the Lower Cretaceous Yixian Formation, Western Liaoning, China 总被引：1，自引：1，他引：0
The abundant fossils of early angiosperms found in the Yixian Formation (125 Ma, Early Cretaceous) have demonstrated unexpectedly high diversity and various reproductive strategies, and thus have shed new light on early angiosperm evolution. Here, using light microscope and scanning electron microscope, we document several fructifications of Baicarpus gen. nov. from Liaoning province, China. Each fructification of the new taxon includes several apocarpous carpels/fruits attached in an urn-formed gynobase. Each fruit/carpel has a persistent straight style and an ovary enclosing a single seed. These fossil plants demonstrate a new floral organization and thus enhance our understanding of the diversity of angiosperms in the Yixian Formation. Together with previously reported ones, this fossil angiosperm suggests an origin time for angiosperms earlier than widely accepted. 相似文献
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The Yixian Formation (the Early Cretaceous) of China has yielded a diverse group of early angiosperms, revealing the charm of angiosperms from the formation is far from finishing. Here we report a fossil angiosperm, Nothodichocarpum gen. et sp. nov, with physically connected female parts, male parts, branches, and leaves with pinnate reticulate venation from the Yixian Formation of Liaoning, China. In addition to the previous reports, this report underscores the diversity of angiosperms in the Early Cretaceous Yixian Formation and earlier origin of angiosperms. The morphological variations in the reproductive parts in different stages allow us to infer the development of this early angiosperm. This fossil plant demonstrates a unique character assemblage that sheds new light on the origin and evolution of carpels. 相似文献
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According to the classic doctrine of angiosperm evolution, the archetype carpel in angiosperms is of plicate form. However, this concept is facing increasing challenges from the systematics based on molecular data, which now takes ascidiate carpel as ancestral. This reorientation in evolutionary thinking cannot be fully achieved unless there is supporting fossil evidence. Here a fruit, named Liaoningfructus, is reported from the famous Yixian Formation (Early Cretaceous, 125 Ma), which yielded several pioneer angiosperms in the past decades. The configuration of the fruit suggests that the carpel giving rise to the fruit is most likely ascidiate, favoring the above reorientation. There are two seeds in the fruit, and at least one of them is served by a vascular bundle arising from the bottom of the fruit, implying a basal placentation in the former carpel, which again is different from the classic thinking. This discovery not only enhances the diversity of angiosperms in the Yixian Formation, but also accelerates the on-going switching of thinking on angiosperm evolution 相似文献
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离龙类是一在形态和生态适应上高度特化的水生—半水生爬行动物双孔亚纲的灭绝支系。离龙目的地理分布局限于北半球,地史分布从侏罗纪一直延续到中新世。辽西是中国最为重要的离龙类化石产地,化石点主要分布于凌源、义县、朝阳和建昌4个地区,尤其以义县地区化石点的分布最为密集。目前辽西已经发现的离龙类包括3科4属5种,其中潜龙和满洲鳄2属的化石仅发现于义县组,而伊克昭龙与戏水龙2属的化石则仅见于九佛堂组。化石证据表明,白垩纪离龙类在辽西范围内的延展分布呈现一个自西向东、由南向北的地理地史演化过程。化石证据也表明辽西的离龙类在较短的时期和较窄的地域范围内经历了一个快速分异演化的过程。长颈潜龙类和短吻满洲鳄类在辽西同时首现于凌源义县组大新房子层,并先后灭绝于义县组的大康堡层和金刚山层。潜龙类最后出现的大康堡层的火山凝灰岩层密集保存了数以千计的潜龙类个体,可能代表该类群于早白垩世发生了与火山喷发活动紧密相关的集群灭绝事件。而后,短吻戏水龙和长吻伊克昭龙同时首现于九佛堂组第2段,并于该组第3段沉积时期内灭绝。整个辽西地域内的离龙类的分布从126～120Ma,在经历了大约6Ma的快速分异演化之后,均于早白垩世阿普第期灭绝。 相似文献
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The Early Cretaceous Jehol Biota, one of the most important Mesozoic lagerstätten in East Asia, is especially well-known for occurrences of fossil feathered dinosaurs and early angiosperms. However, the terrestrial biodiversity, especially the fossil wood record, is poorly known. In this study, several structurally preserved coniferous wood specimens from the Lower Cretaceous Yixian Formation are investigated, based on collections from the Heichengzi Basin in Beipiao of western Liaoning, Northeast China. Four species referred to four genera of fossil wood are described, including Taxodioxylon heichengziense sp. nov., Thujoxylon beipiaoense sp. nov., Sciadopityoxylon liaoningense Ding and Protocedroxylon shengjinbeigouense sp. nov. These new records enlarge the fossil wood diversity of the Yixian Formation up to 10 species in 9 genera, and provide further insights into the forest vegetation composition of the Early Cretaceous Jehol Biota. Systematic analysis of the floral constitution indicates that the petrified forests of the Yixian Formation are dominated by conifers, represented by Araucariaceae, Podocarpaceae, Sciadopityaceae, Pinaceae and Cupressaceae in the western Liaoning region. Palaeoclimatical analysis of the fossil wood assemblage implies that the western Liaoning region was dominated by a cool temperate, wet and seasonal climate with variable interannual water supply in the western Liaoning region during the Early Cretaceous. 相似文献
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A new genus, Cretasyne gen. nov., in the family Lasiosynidae, with two species C. lata sp. nov. and C. longa sp. nov., is described from the Lower Cretaceous Yixian Formation of Inner Mongolia, China. These fossils are the first record of the family from the Yixian Formation and provide significant information on lasiosynid morphology and diversity. The fossil record of Lasiosynidae is also reviewed. 相似文献
8.
The genus Knoblochia is established for fossil insect eggs. The fossils are small, longitudinally ridged, ovoid to round with projections on both ends. Their thin perforated wall is covered by minute papillae, inner surface of the wall is smooth or covered by rectangular files of cells. Fossils assigned here to Knoblochia cretacea were earlier assigned to the genus Spirellea, which encompass a heterogenous complex of small fossils being or resembling angiosperm seeds from the Late Cretaceous. The majority of species of the genus Spirellea clearly represents remains of angiosperms. However, fossils described by Knobloch and Mai (1986) as Spirellea kvacekii are distinct, particularly in having external walls perforated, neither apex nor basal projection showing any absition scar or micropyle in the botanical sense. Attribution of these fossils to insects led us to designate the new name Knoblochia cretacea with a new holotype for fossils of this kind. Comparison of Knoblochia with insect eggs of species of Phasmatodea and Lepidoptera, and seeds of Stemonaceae showed clear affinity to insects. Due to the high amount of extinction among insects since the Cretaceous, the systematic affinity of Knoblochia remains open. 相似文献
9.
HAN Gang LIU Zhongjian LIU Xueling MAO Limi Frédéric M.B. JACQUES WANG Xin 《《地质学报》英文版》2016,90(1):19-29
In contrast to woody habit with secondary growth, truthful herbaceous habit lacking secondary growth is restricted to angiosperms among seed plants. Although angiosperms might have occurred as early as in the Triassic and herbaceous habit theoretically may have been well adopted by pioneer angiosperms, pre-Cretaceous herbs are missing hitherto, leaving the origin of herbs and evolution of herbaceous angiosperms mysterious. Here we report Juraherba bodae gen. et sp. nov, a whole plant herbaceous angiosperm, from the Middle Jurassic (>164 Ma) at Daohugou Village, Inner Mongolia, China, a fossil Lagerst?tten that is worldwide famous for various fossil finds. The angiospermous affinity of Juraherba is ensured by its enclosed ovules/seeds. The plant is small but complete, with physically connected hairy root, stem, leaves, and fructifications. The Middle Jurassic age recommends Juraherba as the earliest record of herbaceous seed plants, demanding a refresh look at the evolutionary history of angiosperms. 相似文献
10.
Darwin described the Cretaceous diversification and subsequent rapid rise of flowering plants (angiosperms) as an “abominable mystery”: how could they have achieved worldwide ecological dominance by early Paleogene times when the oldest angiosperm fossils are only Cretaceous in age? However, recent phylogenetic and palaeobiogeographical analyses have suggested a much earlier, perhaps Triassic origin for the stem angiosperms. We suggest that the fossil record is accurately reflecting the rapid diversification of the crown angiosperms that molecular data suggests occurred in Cretaceous–early Palaeogene times, and which coincides with similar explosive diversifications that occurred in other parts of the terrestrial biota including insects, birds and mammals. Early, stem angiosperms are poorly represented in the fossil record for a combination of taphonomic and ecological reasons. We conclude that the reported evidence shows that the Darwin's “mystery” is in fact no mystery and confirms that it merely requires an appropriate reading of the fossil record. 相似文献