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Sinosachites
''Sinosachites'' is a genus of 'halkieriid' known only from sclerites; these have internal chambers that are sub-perpendicular to the central canal, to which they are connected by narrow channels. The chambers are the same diameter, ~40 µm, as the longitudinal canals in '' Australohalkieria''; their greater number and arrangement as lateral rather than longitudinal bodies reflects the greater size of the ''Sinosachites'' sclerites, which measure about 1–2 mm in length. The sclerites are probably synonymous with ''Thambetolepis'', which was originally described from Australia. Left-hand and right-hand sclerites exist, so the animal was bilaterally symmetrical; as in ''Halkieria The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the smal ...'', palmate, cultrate and siculate sclerit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halkieriid
The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the small shelly fossil assemblages. The best known species is ''Halkieria evangelista'', from the North Greenland Sirius Passet Lagerstätte, in which complete specimens were collected on an expedition in 1989. The fossils were described by Simon Conway Morris and John Peel in a short paper in 1990 in the journal ''Nature''. Later a more thorough description was undertaken in 1995 in the journal ''Philosophical Transactions of the Royal Society of London'' and wider evolutionary implications were posed. The group is sometimes equated to Sachitida, although as originally envisaged, this group includes the wiwaxiids and is thus equivalent to the Halwaxiida. History of discovery Armor plates called "sclerites" had long been known as elements of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halkieria
The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the small shelly fossil assemblages. The best known species is ''Halkieria evangelista'', from the North Greenland Sirius Passet Lagerstätte, in which complete specimens were collected on an expedition in 1989. The fossils were described by Simon Conway Morris and John Peel in a short paper in 1990 in the journal ''Nature''. Later a more thorough description was undertaken in 1995 in the journal ''Philosophical Transactions of the Royal Society of London'' and wider evolutionary implications were posed. The group is sometimes equated to Sachitida, although as originally envisaged, this group includes the wiwaxiids and is thus equivalent to the Halwaxiida. History of discovery Armor plates called "sclerites" had long been known as elements of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thambetolepis
''Thambetolepis'' is a dubious genus of sachitid halkieriid from the Cambrian (530-513 Ma). The genus '' Sinosachites'' may have been the same as ''Thambetolepis''. The sclerites of ''Sinosachites'' are probably synonymous with ''Thambetolepis'', which was originally described from Australia. Left-hand and right-hand sclerites exist, so the animal was bilaterally symmetrical; as in ''Halkieria The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the sma ...'', palmate, cultrate and siculate sclerite morphologies exist. The chambers are the same diameter, ~40 µm, as the longitudinal canals in '' Australohalkieria''; their greater number and arrangement as lateral rather than longitudinal bodies reflects the greater size of the ''Sinosachites'' sclerites, which measure about 1–2 mm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australohalkieria
''Australohalkieria'' (meaning "southern ''Halkieria''") is an extinct genus of halkieriid from Australia and Antarctica. Description ''Australohalkieria superstes'' This species, named by Porter in 2004, is the most complete and abundant Australian halkieriid species. The sclerites assigned to this species are convex on the upper surface and concave on the lower. They may also curve within their own plane, and they overlap so that the concave side of each is partly covered by the convex side of the next one. The internal cavity within ''Australohalkieria'' is more complicated that the simple tube in ''Halkieria''; about half-way up the sclerite, the cylindrical tube splits into a pair of longitudinal canals, with the central canal flattening; the canals don't seem to be connected. The walls also have a different microscopic structure. In ''A. superstes'' the central canals of sclerites are flattened on their upper surfaces, and this produces a depression on the upper surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 1981
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinct Molluscs
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional extinction, capacity to breed and recover may have been lost before this point. Because a species' potential Range (biology), range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxon, Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the Fossil, fossil record) after a period of apparent absence. More than 99% of all species that ever Life, lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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