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Quadratapora
''Quadratapora'' is a genus of lobopodian known only from its biomineralized dorsal plates, which somewhat resemble those of ''Microdictyon''. Its fossils date to the Tommotian Stage 2 of the Cambrian is the unnamed upper stage of the Terreneuvian Series. It lies atop the Fortunian and below Stage 3 of the Cambrian. It is commonly referred to as the Tommotian, after the Cambrian stratigraphy of Siberia. Neither the upp ..., representing (perhaps along with '' Rhombocorniculum'') the earliest record of lobopodians. References Cambrian animals Lobopodia Prehistoric protostome genera {{paleo-protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobopodia
The lobopodians, members of the informal group Lobopodia (from the Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, worm-like fossil panarthropods such as '' Aysheaia'' and '' Hallucigenia''. The oldest near-complete fossil lobopodians date to the Lower Cambrian; some are also known from Ordovician, Silurian and Carboniferous Lagerstätten. Some bear toughened claws, plates or spines, which are commonly preserved as carbonaceous or mineralized microfossils in Cambrian strata. The grouping is considered to be paraphyletic, as the three living panarthropod groups (Arthropoda, Tardigrada and Onychophora) are thought to have evolved from lobopodian ancestors. Definitions The Lobopodian concept vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobopodia
The lobopodians, members of the informal group Lobopodia (from the Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, worm-like fossil panarthropods such as '' Aysheaia'' and '' Hallucigenia''. The oldest near-complete fossil lobopodians date to the Lower Cambrian; some are also known from Ordovician, Silurian and Carboniferous Lagerstätten. Some bear toughened claws, plates or spines, which are commonly preserved as carbonaceous or mineralized microfossils in Cambrian strata. The grouping is considered to be paraphyletic, as the three living panarthropod groups (Arthropoda, Tardigrada and Onychophora) are thought to have evolved from lobopodian ancestors. Definitions The Lobopodian concept vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsum (anatomy)
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axis, anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate (anatomy)
A plate in animal anatomy may refer to several things: Flat bones (examples: bony plates, dermal plates) of vertebrates * an appendage of the Stegosauria group of dinosaurs * articulated armoured plates covering the head of thorax of Placodermi (literally "plate-skinned"), an extinct class of prehistoric fish (including skull, thoracic and tooth plates) * bony shields of the Ostracoderms (armored jawless fishes) such as the dermal head armour of members of the class Pteraspidomorphi that include dorsal, ventral, rostral and pineal plates * plates of a carapace, such as the dermal plates of the shell of a turtle * dermal plates partly or completely covering the body of the fish in the order Gasterosteiformes that includes the sticklebacks and relatives * plates of dermal bones of the armadillo * Zygomatic plate, a bony plate derived from the flattened front part of the zygomatic arch (cheekbone) in rodent anatomy Other flat structures * hairy plate-like keratin scales of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdictyon
''Microdictyon'' is an extinct armoured worm-like animal coated with net-like scleritic plates, known from the Early Cambrian Maotianshan shale of Yunnan China and other parts of the world. ''Microdictyon'' is part of the ill-defined taxon – Lobopodia – that includes several other odd worm-like animals that resembling worm with legs, such as '' Hallucigenia'', '' Onychodictyon'', ''Cardiodictyon'', '' Luolishania'', and ''Paucipodia''. The isolated sclerites of ''Microdictyon'' are known from other Lower Cambrian deposits. ''Microdictyon'' sclerites appear to have moulted; one sclerite seems to have been preserved during ecdysis.Figured in ''Microdictyon sinicum'' (Chen, Hou and Lu, 1989) is typical. The wormlike animal has ten pairs of sclerites (suggestions that these may be eyes or eye-like structures have no weight) on the sides, matched to a pair of tentacle-like feet below. The head and posterior are tubular and featureless. Species composition *Type s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tommotian
Stage 2 of the Cambrian is the unnamed upper stage of the Terreneuvian Series. It lies atop the Fortunian and below Stage 3 of the Cambrian. It is commonly referred to as the Tommotian, after the Cambrian stratigraphy of Siberia. Neither the upper nor lower boundary has yet been defined by the International Commission on Stratigraphy. The preferred definitions for the lower boundary are the first appearance of the molluscs '' Watsonella crosbyi'' or '' Aldanella attleborensis'' around million years ago. The proposed upper boundary might be the first appearance of trilobites around million years ago. Possible candidates for a GSSP include the first appearance of ''Watsonella crosbyi'' in the Zhujiaqing Formation (朱家庆组) in Yunnan, China or the Pestrotsvet Formation near the Aldan River on the Siberian Platform Siberia, also known as Angaraland (or simply Angara) and Angarida, is an ancient craton in the heart of Siberia. Today forming the Central Siberian Plateau, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhombocorniculum
''Rhombocorniculum'' is a species of small shelly fossil comprising twisted ornamented cones. It has been described from the Comely limestone and elsewhere. ''R. cancellatum'' straddles the Atdabanian/Botomian boundary. The structure of its inner layer suggests that its phosphatic fibres formed within a flexible organic matrix. Taxonomy Three species are recognized — in stratigraphic succession: ''R. insolutum'', ''R. cancellatum'' (=''R. walliseri''), and ''R. spinosus'' (=''Rushtonites spinosus''). Landing (1995) refers ''R. insolutum'' to the strictocorniculids, along with '' Rushtonites''. Hinz (1987) considers ''insolutum'' to fall within the variability seen in ''cancellatum''. Affinity Based on details of the ornament and construction, ''Rhombocorniculum'' is interpreted as the spines of a ''Hallucigenia''-like lobopodian worm. See also *''Mongolitubulus ''Mongolitubulus'' is a form genus encapsulating a range of ornamented conical small shelly fossils ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Animals
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
