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Cestites Mirabilis Fertile
The Douglas Lake Member is a geologic unit of Stratigraphic unit#Member, member rank of the Lenoir Limestone that overlies the Mascot Dolomite and underlies typical nodular member of the Lenoir Limestone in Douglas Lake, Tennessee, region. It fills depressions that are part of a regional unconformity at the base of Middle Ordovician strata, locally the Lenoir Limestone, that separates them from the underlying Lower Ordovician strata, locally the Knox Group.U.S. Geological Survey, 2020Geologic Unit: Douglas Lake Walker, K.R., Steinhauff, D.M., and Roberson, K.E., 1992. ''Uppermost Knox Group, the Knox unconformity, the Middle Ordovician transition from shallow shelf to deeper basin at Dandridge, Tennessee'', In Driese, S.G., and others, eds., ''Paleosols, paleoweathering surfaces, and sequence boundaries'', ''University of Tennessee, Departm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasmataspis
''Chasmataspis'' is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods. It was found in the Early Ordovician deposits of Tennessee, United States. Morphology Just like other chasmataspidids, the body of ''Chasmataspis'' compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen. Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli. ''Chasmataspis'' characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments. Rows of tubercles and spines run through the axial and lateral regions of opisthosoma. The body terminated with a spine-like telson. There is no body fossils of ''Chasmataspis'' with unambiguous appendages being discovered. The only evidence were 2 specimens of disarticulated, claw-bearing appendages discovered from the same stratum In geology and related fields, a stra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalbrookdale Formation
Coalbrookdale Formation, earlier known as Wenlock Shale or Wenlock Shale Formation and also referred to as Herefordshire Lagerstätte in palaeontology, is a fossil-rich deposit ('' Konservat-Lagerstätte'') in Powys and Herefordshire at the England–Wales border in UK. It belongs to the Wenlock Series of the Silurian Period within the Homerian Age (about 430 million years ago). It is known for its well-preserved fossils of various invertebrate animals many of which are in their three-dimensional structures. Some of the fossils are regarded as earliest evidences and evolutionary origin of some of the major groups of modern animals. Roderick Murchison first described the geological setting of Coalbrookdale Formation by which he gave the name Silurian in 1935, referring to the Silures, a Celtic tribe of Wales. It is assigned to the Wenlock Group in 1978 based on the age of crustacean fossils found around the region. Robert J. King of the University of Leicester discovered the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanobacterial
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae. Cyanobacteria are probably the most numerous taxon to have ever existed on Earth and the first organisms known to have produced oxygen, having appeared in the middle Archean eon and apparently originated in a freshwater or terrestrial environment. Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacteria a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leiosporocerotaceae
''Leiosporoceros dussii'' is the only species in the hornwort genus ''Leiosporoceros''. The species is placed in a separate family, order, and class for being " genetically and morphologically distinct from all other hornwort lineages." Cladistic analysis of genetic data supports a position at the very base of the hornwort clade. Physical characteristics that distinguish the group include unusually small spores that are ''monolete'' and unornamented. Additionally, there are unique strands of ''Nostoc'' (cyanobacteria) that grow inside the plant parallel with its direction of growth. Unlike other hornworts with symbiotic cyanobacteria that enters through mucilage clefts, the mucilage clefts in Leiosporoceros is only present in young plants and then closes permanently once the cyanobacterial colonies have been established. Also mycorrhiza and pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cestites Mirabilis Fertile
The Douglas Lake Member is a geologic unit of Stratigraphic unit#Member, member rank of the Lenoir Limestone that overlies the Mascot Dolomite and underlies typical nodular member of the Lenoir Limestone in Douglas Lake, Tennessee, region. It fills depressions that are part of a regional unconformity at the base of Middle Ordovician strata, locally the Lenoir Limestone, that separates them from the underlying Lower Ordovician strata, locally the Knox Group.U.S. Geological Survey, 2020Geologic Unit: Douglas Lake Walker, K.R., Steinhauff, D.M., and Roberson, K.E., 1992. ''Uppermost Knox Group, the Knox unconformity, the Middle Ordovician transition from shallow shelf to deeper basin at Dandridge, Tennessee'', In Driese, S.G., and others, eds., ''Paleosols, paleoweathering surfaces, and sequence boundaries'', ''University of Tennessee, Departm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametophyte
A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes. Algae In some multicellular green algae ('' Ulva lactuca'' is one example), red algae and brown algae, sporophytes and gametophytes may be externally indistinguishable (isomorphic). In ''Ulva'', the gametes are isogamous, all of one size, shape and general morphology. Land plant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marchantiaceae
Marchantiaceae is a family of liverworts in order Marchantiales. It contains a single genus ''Marchantia''. Genera in Marchantiaceae Until recently, three genera were included in the Marchantiaceae: * '' Bucegia'' Radian 1903 * ''Marchantia'' Linnaeus 1753 * '' Preissia'' Corda 1829 non Opiz 1852 However, the genera ''Bucegia'' and ''Preissia'' have since been merged into ''Marchantia'', leaving only the single genus in the family.Long, David G., Laura L. Forrest, Juan Carlos Villarreal, Barbara J. Crandall-Stotler. 2016. "Taxonomic changes in Marchantiaceae, Corsiniaceae and Cleveaceae (Marchantiidae, Marchantiophyta)". ''Phytotaxa'' 252 (1): 077–080. A number of additional genera have been moved to other families: * '' Asterella'', now in family Aytoniaceae * ''Conocephalum'', now in family Conocephalaceae ''Conocephalum'' is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae.AKIYAMA, H. (2022) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liverwort
Liverworts are a group of non-vascular land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information. The division name was derived from the genus name '' Marchantia'', named after his father by French botanist Jean Marchant. It is estimated that there are about 9000 species of liverworts. Some of the more familiar species grow as a flattened leafless thallus, but most species are leafy with a form very much like a flattened moss. Leafy species can be distinguished from the apparently similar mosses on the basis of a number of features, including their single-celled rhizoids. Leafy liverworts also differ from most (but not all) mosses in that their leaves never have a costa (present in many mosses) and may bear marginal cilia (very rare in mosses). Other differences are not universal for all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compression Fossils
A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason for this is that physical compression of the rock often leads to distortion of the fossil. The best fossils of leaves are found preserved in fine layers of sediment that have been compressed in a direction perpendicular to the plane of the deposited sediment. Since leaves are basically flat, the resulting distortion is minimal. Plant stems and other three-dimensional plant structures do not preserve as well under compression. Typically, only the basic outline and surface features are preserved in compression fossils; internal anatomy is not preserved. These fossils may be studied while still partially entombed in the sedimentary rock matrix where they are preserved, or once lifted out of the matrix by a peel or transfer technique. Compre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ediacaran Biota
The Ediacaran (; formerly Vendian) biota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period (). These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined. The Ediacaran biota may have undergone evolutionary radiation in a proposed event called the Avalon explosion, . This was after the Earth had thawed from the Cryogenian period's extensive glaciation. This biota largely disappeared with the rapid increase in biodiversity known as the Cambrian explosion. Most of the currently existing body plans of animals first appeared in the fossil record of the Cambrian rather than the Ediacara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gregory Retallack
Gregory John Retallack (born 8 November 1951) is an Australian paleontologist, geologist, and author who specializes in the study of fossil soils ( paleopedology). His research has examined the fossil record of soils though major events in Earth history, extending back some 4.6 billion years. He has written two textbooks on paleopedology. Biography Retallack moved with his family from Hobart, Tasmania at age 4. He grew up in Hurstville and then Epping, in the suburbs of Sydney. He attended The King's School, Parramatta, then studied biology and paleontology at Macquarie University. He received a BSc Hons with University Medal in 1974 from the University of New England (Australia) and a PhD in 1978 in geology from the same university. After a postdoctoral fellowship at Indiana University Bloomington he joined the faculty at the University of Oregon in 1981. He was a professor in the Department of Geological Sciences since 1992, and Director of the Condon Collection of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
