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Yimaia
''Yimaia'' is a extinct genus of Ginkgoalean tree, and the only member of the family Yimaiaceae. In botanical form classification, its a form taxon for ginkgoalean ovulate organs. ''Yimaia'' species are distinguished from other Ginkgoales by the presence of "Ovulate organs consisting of a peduncle and up to eight or nine terminal, sessile, contiguous and orthotropous (straight, upright and with a micropyle at apex) ovules." The ovules are associated with leaves of either ''Baiera'' or ''Ginkgoites'' leaf morphospecies. Fossils have been found in Middle Jurassic deposits in China. Species * ''Yimaia capituliformis'' Zhou, Zheng and Zhang, 2006 Daohugou Bed, China, Callovian Associated with leaves of ''Ginkgoites'' type *''Yimaia qinghaiensis'' Wu, Yang and Zhou, 2006 Shimengou Formation, Qinghai, China, Middle Jurassic Associated with leaves of ''Baiera furcata'' type. * ''Yimaia recurva'' (type) Zhou et Zhang, 1988 Yima Formation, Henan, China, Middle Jurassic The Middle Ju ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ginkgoales
Ginkgoales are a gymnosperm order containing only one extant species: ''Ginkgo biloba'', the ginkgo tree. It is monotypic, (the only taxon) within the class Ginkgoopsida, which itself is monotypic within the division Ginkgophyta . The order includes five families, of which only Ginkgoaceae remains extant. History Ginkgophyta and Cycadophyta have a very ancient divergence dating to the early Carboniferous. The earliest representative of the group in the fossil record is probably '' Trichopitys'' from the Asselian (299-293 million years ago) of France. The earliest representatives of ''Ginkgo'', represented by reproductive organs similar to the living species, first appear in the Middle Jurassic, alongside other, related forms such as ''Yimaia'' and ''Karkenia'', which have differently arranged reproductive structures and seeds associated with ''Ginkgo''-like leaves. The diversity of Ginkgoales declined during the Late Cretaceous and Cenozoic, coincident with the rise of flowerin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. In contrast, an oligotypic taxon contains more than one but only a very few subordinate taxa. Examples Just as the term ''monotypic'' is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within a family. Some examples of monotypic groups are: Plants * In the order Amborellales, there is only one family, Amborellaceae and there is only one genus, '' Amborella'', and in this genus there is only one species, namely ''Amborella trichopoda. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Form Classification
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of science is to move "form taxa" to biological taxa whose affinity is known. Form taxonomy is restricted to fossils that preserve too few characters for a conclusive taxonomic definition or assessment of their biological affinity, but whose study is made easier if a binomial name is available by which to identify them. The term "form classification" is preferred to "form taxonomy"; taxonomy suggests that the classification implies a biological affinity, whereas form classification is about giving a name to a group of morphologically-similar organisms that may not be related. A "parataxon" (not to be confused with parataxonomy), or "sciotaxon" (Gr. "shadow taxon"), is a classification based on incomplete data: for instance, the larval stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Form Taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of science is to move "form taxa" to biological taxa whose affinity is known. Form taxonomy is restricted to fossils that preserve too few characters for a conclusive taxonomic definition or assessment of their biological affinity, but whose study is made easier if a binomial name is available by which to identify them. The term "form classification" is preferred to "form taxonomy"; taxonomy suggests that the classification implies a biological affinity, whereas form classification is about giving a name to a group of morphologically-similar organisms that may not be related. A "parataxon" (not to be confused with parataxonomy), or "sciotaxon" (Gr. "shadow taxon"), is a classification based on incomplete data: for instance, the larval stage o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center. The female gametophyte — specifically termed a ''megagametophyte''— is also called the ''embryo sac'' in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule. Location within the plant In flowering plants, the ovule is located inside the portion of the flower called the gynoecium. The ovary of the gynoecium produces one or more ovules and ultimately becomes the fruit wall. Ovules are attached to the placenta in the ovary through a stalk-like structure known as a ''funiculus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peduncle (botany)
In botany, a peduncle is a stalk supporting an inflorescence or a solitary flower, or, after fecundation, an infructescence or a solitary fruit. The peduncle sometimes has bracts (a type of cataphylls) at nodes. The main axis of an inflorescence above the peduncle is the rachis. There are no flowers on the peduncle but there are flowers on the rachis. When a peduncle arises from the ground level, either from a compressed aerial stem or from a subterranean stem (rhizome, tuber, bulb, corm), with few or no bracts except the part near the rachis or receptacle, it is referred to as a scape. The acorns of the pedunculate oak are borne on a long peduncle, hence the name of the tree. See also *Pedicel (botany) *Scape (botany) In botany, a scape is a peduncle arising from a subterranean or very compressed stem, with the lower internodes very long and hence few or no bracts except the part near the rachis or receptacle. Typically it takes the form of a long, leafles ... Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baiera
''Baiera'' is a genus of prehistoric gymnosperms in the order Ginkgoales. It is one of the oldest fossil foliage types of Ginkgoales, and is related to the genera ''Ginkgo'' and ''Ginkgoites''. Fossils of ''Baiera'' are found worldwide, and have been known from the Permian to the Cretaceous. Description ''Baiera'' species are characterized by fan-shaped leaves,Pott, Christian & Burgh, J. & van Konijnenburg-van Cittert, Johanna. (2016). New Ginkgophytes from the Upper Triassic–Lower Cretaceous of Spitsbergen and Edgeøya (Svalbard, Arctic Norway): The History of Ginkgoales on Svalbard. International Journal of Plant Sciences. 177. 175-197. 10.1086/684194. are deeply lobed into four segments, deeply incised into slender segments, and are distinguished from ''Sphenobaiera'' by a petiole. ''B. africana'' is characterized by its symmetrical and triangular leaves. Classification Karl Friedrich Wilhelm Braun first introduced the name ''Baiera'' in 1843 to refer to fossils in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ginkgoites
''Ginkgoites'' is a genus that refers to extinct plants belonging to Ginkgoaceae. Fossils of these plants have been found around the globe during the Triassic, Jurassic, Cretaceous, with fossils also known from the Paleogene. The name was created as a form genus in 1919 by Albert Seward who stated: "I ... propose to employ the name ''Ginkgoites'' for leaves that it is believed belong either to plants generically identical with ''Ginkgo ''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus with ...'' or to very closely allied types". References Ginkgophyta Prehistoric gymnosperm genera Cretaceous plants Jurassic plants Triassic plants Norian first appearances Campanian genus extinctions Prehistoric plants of South America Permian life of South America Triassic life of South Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland,British Geological Survey. 2011Stratigraphic framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf: research report RR/11/06 British Geological Survey, Keyworth, Nottingham. the Daohugou Beds in China, the Itat Formation in Russia, and the Isalo III Formation of western Madagascar. Paleogeography During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean. A subduction zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and borders fourteen countries by land, the most of any country in the world, tied with Russia. Covering an area of approximately , it is the world's third largest country by total land area. The country consists of 22 provinces, five autonomous regions, four municipalities, and two Special Administrative Regions (Hong Kong and Macau). The national capital is Beijing, and the most populous city and financial center is Shanghai. Modern Chinese trace their origins to a cradle of civilization in the fertile basin of the Yellow River in the North China Plain. The semi-legendary Xia dynasty in the 21st century BCE and the well-attested Shang and Zhou dynasties developed a bureaucratic political system to serve hereditary monarchies, or dyna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daohugou Bed
The Haifanggou Formation (), also known as the Jiulongshan Formation (), is a fossil-bearing rock deposit located near Daohugou () village of Ningcheng County, in Inner Mongolia, northeastern China. The formation consists of coarse conglomerates, sandstone, mudstone, and thin coal layers deposited in deltaic and lacustrine environments. The formation dates to the Callovian of the Middle Jurassic to the Oxfordian of the Late Jurassic. The most prominent locality of the Haifanggou Formation are the Daohugou Beds, located near the village of Daohugou in southeastern Inner Mongolia. Other localities include Wuhuaxigou, Chentaizi, Jiangzhangzi, Wubaiding, Guancaishan, Haifenggou, Fanzhangzi, and Zhuanshanzi. Dating Daohugou bed The age of the Daohugou bed has been debated, and a number of studies, using different methodologies, have reached conflicting conclusions. Various papers have placed the fossils here as being anywhere from the Middle Jurassic period (169 million ye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callovian
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian. Stratigraphic definitions The Callovian Stage was first described by French palaeontologist Alcide d'Orbigny in 1852. Its name derives from the latinized name for Kellaways Bridge, a small hamlet 3 km north-east of Chippenham, Wiltshire, England. The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus ''Kepplerites'' first appears, which is the base of the biozone of '' Macrocephalites herveyi''. A global reference profile (a GSSP) for the base had in 2009 not yet been assigned. The top of the Callovian (the base of the Oxfordian) is at the first appearance of ammonite species '' Brightia thuouxensis''. Subdivision The Callovian is often subdivided into three substages ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
