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Douglasocaris
''Douglasocaris'' is a genus of bivalved arthropod from the Middle Ordovician (Darriwilian, 460 million years old) Douglas Lake Member of the Lenoir Limestone from Douglas Dam Tennessee. Description ''Douglasocaris'' has alternatively been considered a phyllocarid or a notostracan. References Fossils of Tennessee Prehistoric arthropod genera {{paleo-crustacean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglasocaris Collinsi
''Douglasocaris'' is a genus of bivalved arthropod from the Middle Ordovician (Darriwilian, 460 million years old) Douglas Lake Member of the Lenoir Limestone from Douglas Dam Tennessee. Description ''Douglasocaris'' has alternatively been considered a phyllocarid or a notostracan. References Fossils of Tennessee Prehistoric arthropod genera {{paleo-crustacean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglasocaris Part
''Douglasocaris'' is a genus of bivalved arthropod from the Middle Ordovician (Darriwilian, 460 million years old) Douglas Lake Member of the Lenoir Limestone from Douglas Dam Tennessee. Description ''Douglasocaris'' has alternatively been considered a phyllocarid or a notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and '' Lepidurus'', are considered living fossils, with similar forms having existed sinc ...n. References Fossils of Tennessee Prehistoric arthropod genera {{paleo-crustacean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglasocaris Counterpart
''Douglasocaris'' is a genus of bivalved arthropod from the Middle Ordovician (Darriwilian, 460 million years old) Douglas Lake Member of the Lenoir Limestone from Douglas Dam Tennessee. Description ''Douglasocaris'' has alternatively been considered a phyllocarid or a notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and '' Lepidurus'', are considered living fossils, with similar forms having existed sinc ...n. References Fossils of Tennessee Prehistoric arthropod genera {{paleo-crustacean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglas Lake Member
The Douglas Lake Member is a geologic unit of 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, Department of Geological Scienc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notostraca
The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and '' Lepidurus'', are considered living fossils, with similar forms having existed since the Devonian. They have a broad, flat carapace, which conceals the head and bears a single pair of compound eyes. The abdomen is long, appears to be segmented and bears numerous pairs of flattened legs. The telson is flanked by a pair of long, thin caudal rami. Phenotypic plasticity within taxa makes species-level identification difficult, and is further compounded by variation in the mode of reproduction. Notostracans are omnivores living on the bottom of temporary pools and shallow lakes. Description Notostracans are long, with a broad carapace at the front end, and a long, slender abdomen. This gives them a similar overall shape to a tadpole, from which the common name ''tadpole shrimp'' derives. The carapace is dorso-ventrally flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animalia
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropoda
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an exoskeleton, external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malacostraca
Malacostraca (from New Latin; ) is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, amphipods, mantis shrimp, tongue-eating lice and many other less familiar animals. They are abundant in all marine environments and have colonised freshwater and terrestrial habitats. They are segmented animals, united by a common body plan comprising 20 body segments (rarely 21), and divided into a head, thorax, and abdomen. Etymology The name Malacostraca was coined by a French zoologist Pierre André Latreille in 1802. He was curator of the arthropod collection at the National Museum of Natural History in Paris. The name comes from the Greek roots (', meaning "soft") and (', meaning "shell"). The name is misleading, since the shell is soft only immediately after moulting, and is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian Pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darriwilian
The Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species ''Undulograptus austrodentatus'' around million years ago. It lasted for about 8.9 million years until the beginning of the Sandbian around million years ago. This stage of the Ordovician was marked by the beginning of the Andean-Saharan glaciation. Naming The name Darriwilian is derived from Darriwil, a parish in County of Grant, Victoria (Australia). The name was proposed in 1899 by Thomas Sergeant Hall. GSSP The GSSP of the Darriwilian is the Huangnitang Section () near the village Huangnitang, 3.5 km southwest of Changshan County Town (Zhejiang, China). It is an outcrop of the Ningkuo Formation, consisting of mainly black shale. The lower boundary of the Darriwilian is defined as the first appearance datum of the graptolite s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lenoir Limestone
The Lenoir Limestone is a geologic formation in Virginia. It preserves fossils dating back to the Ordovician period. See also * List of fossiliferous stratigraphic units in Virginia * Paleontology in Virginia Paleontology in Virginia refers to paleontological research occurring within or conducted by people from the U.S. state of Virginia. The geologic column in Virginia spans from the Cambrian to the Quaternary. During the early part of the Paleozoic ... References * Ordovician geology of Virginia {{Virginia-geologic-formation-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
