|
Hamitidae
''Hamites'' (":wikt:Hamites, hook-like") is a genus of heteromorph ammonite that evolved late in the Aptian stage of the Early Cretaceous and lasted into the Cenomanian stage of the Late Cretaceous. The genus is almost certainly paraphyletic but remains in wide use as a "catch all" for heteromorph ammonites of the superfamily Turrilitoidea that do not neatly fit into the more Synapomorphy, derived groupings. In an attempt to identify clades within the genus, it has been divided up into a series of new genera or subgenera by different Paleontology, palaeontologists, including ''Eohamites'', ''Hamitella'', ''Helicohamites'', ''Lytohamites'', ''Planohamites'', ''Psilohamites'', and ''Sziveshamites''. The type species is ''Hamites attenuatus'' from the early Albian, named by James Sowerby in his ''Mineral Conchology of Great Britain'' of 1814, although the genus itself was created by James Parkinson in his 1811 book ''Organic Remains of the Former World''. This James Parkinson is bes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteromorph Ammonites
The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and became one of the most distinctive components of Cretaceous marine faunas. They have been recorded from every continent and many are used as zonal or index fossils. The most distinctive feature of the majority of the Ancyloceratina is the tendency for most of them to have shells that are not regular spirals like most other ammonites. These irregularly-coiled ammonites are called heteromorph ammonites, in contrast to regularly coiled ammonites, which are called homomorph ammonites. Biology The biology of the heteromorph ammonites is not clear, but one certainty is that their uncoiled shells would have made these forms very poor swimmers. Open shells, particularly ones with spines and ribs, create a lot of drag; but more importantly, the orient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turrilitoidea
Turrilitoidea is a diverse superfamily of Cretaceous ammonites generally considered as heteromorphic and commonly included in the suborder Ancyloceratina. Shells of this diverse group do not coil planospirally, as typical for most ammonitida, ammonites, but rather take on a variety of unique forms. Separation of Turrilitoidea along with Ptychoceratoidea and Scaphatoidea into a different suborder, Turrilitina, was proposed by Beznosov and Mikhailova in 1983 however this view is not accepted by most authors. Some, such as the eponymous ''Turrilites'', coiled helically, like an auger shell, while others, such as ''Hamites (genus), Hamites'', had shells with long straight sections, while the one-of-a-kind ''Nipponites'' coiled in a way so as to appear as a ball of knots. As with other ammonites, the last of the Turrilitoidea had perished by the end of the Cretaceous during the Cretaceous–Paleogene extinction event. References * Arkell ''et al.'', 1957. Mesozoic Ammonoidea,' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Radiation
An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations. Examples Perhaps the most familiar example of an evolutionary radiation is that of placental mammals immediately after the extinction of the non-avian dinosaurs at the end of the Cretaceous, about 66 million years ago. At that time, the placental mammals were mostly small, insect-eating animals similar in size and shape to modern shrews. By the Eocene (58–37 million years ago), they had evolved into such diverse forms as bats, whales, and horses. Other familiar radiations include the Avalon Explosion, the Cambrian Explosion, the Great Ordovician Biodiversification Event, the Carboniferous-Earliest Perm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient animal locomotion, locomotion. The tentacles are armed with Cnidocyte, stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex Biological life cycle, life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp (zoology), polyp phase before reaching sexual maturity. Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine habitats, marine, but some hydrozoans with a simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales. Marine plankton include bacteria, archaea, algae, protozoa and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in the freshwaters of lakes and rivers. Plankton are usually thought of as inhabiting water, but there are also airborne versions, the aeroplankton, that live part of their lives drifting in the atmosphere. These include plant spores, pollen and wind-scattered seeds, as well as microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (physics)
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerated dim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper Clip
A paper clip (or paperclip) is a tool used to hold sheets of paper together, usually made of steel wire bent to a looped shape (though some are covered in plastic). Most paper clips are variations of the ''Gem'' type introduced in the 1890s or earlier, characterized by the almost two full loops made by the wire. Common to paper clips proper is their utilization of torsion and elasticity in the wire, and friction between wire and paper. When a moderate number of sheets are inserted between the two "tongues" of the clip, the tongues will be forced apart and cause torsion in the bend of the wire to grip the sheets together. They are usually used to bind papers together for productivity and portability. Shape and composition Paper clips usually have an oblong shape with straight sides, but may also be triangular or circular, or have more elaborate shapes. The most common material is steel or some other metal, but molded plastic is also used. Some other kinds of paper clips use a two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hamites
Hamites is the name formerly used for some Northern and Horn of Africa peoples in the context of a now-outdated model of dividing humanity into different races which was developed originally by Europeans in support of colonialism and slavery. The term was originally borrowed from the Book of Genesis, where it is used for the descendants of Ham, son of Noah. The term was originally used in contrast to the other two proposed divisions of mankind based on the story of Noah: Semites and Japhetites. The appellation ''Hamitic'' was applied to the Berber, Cushitic, and Egyptian branches of the Afroasiatic language family, which, together with the Semitic branch, was thus formerly labelled "Hamito-Semitic". However, since the three Hamitic branches have not been shown to form an exclusive ( monophyletic) phylogenetic unit of their own, separate from other Afroasiatic languages, linguists no longer use the term in this sense. Each of these branches is instead now regarded as an indep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parkinson's Disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms become more common. The most obvious early symptoms are tremor, rigidity, slowness of movement, and difficulty with walking. Cognitive and behavioral problems may also occur with depression, anxiety, and apathy occurring in many people with PD. Parkinson's disease dementia becomes common in the advanced stages of the disease. Those with Parkinson's can also have problems with their sleep and sensory systems. The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain, leading to a dopamine deficit. The cause of this cell death is poorly understood, but involves the build-up of misfolded proteins into Lewy bodies in the neurons. Collectively, the main motor symptoms are also known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Parkinson
James Parkinson (11 April 175521 December 1824) was an English surgeon, apothecary, geologist, palaeontologist and political activist. He is best known for his 1817 work ''An Essay on the Shaking Palsy'', in which he was the first to describe "paralysis agitans", a condition that would later be renamed Parkinson's disease by Jean-Martin Charcot. Early life James Parkinson was born April 11, 1755 in Shoreditch, London, England. He was the son of John Parkinson, an apothecary and surgeon practising in Hoxton Square in London, and the oldest of five siblings, including his brother William and his sister Mary Sedgwick. In 1784 Parkinson was approved by the City of London Corporation as a surgeon. On 21 May 1783, he married Mary Dale, with whom he subsequently had eight children; two did not survive past childhood. Soon after he was married, Parkinson succeeded his father in his practice in 1 Hoxton Square. Politics In addition to his flourishing medical practice, Parkinson had a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Sowerby
James Sowerby (21 March 1757 – 25 October 1822) was an English naturalist, illustrator and mineralogist. Contributions to published works, such as ''A Specimen of the Botany of New Holland'' or ''English Botany'', include his detailed and appealing plates. The use of vivid colour and accessible texts were intended to reach a widening audience in works of natural history. Biography James Sowerby was born in Lambeth, London, his parents were named John and Arabella. Having decided to become a painter of flowers his first venture was with William Curtis, whose ''Flora Londinensis'' he illustrated. Sowerby studied art at the Royal Academy and took an apprenticeship with Richard Wright. He married Anne Brettingham De Carle and they were to have three sons: James De Carle Sowerby (1787–1871), George Brettingham Sowerby I (1788–1854) and Charles Edward Sowerby (1795–1842), the Sowerby family of naturalists. His sons and theirs were to contribute and continue the enormous vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
