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Hypogeomys Australis
''Hypogeomys australis'' is an extinct rodent from central and southeastern Madagascar. First described in 1903, it is larger than its close relative, the living '' Hypogeomys antimena'', which occurs further west, but otherwise similar. Average length of the femur (upper leg bone) is 72.1 mm, compared to 63.8 mm in ''H. antimena''. One of the few extinct rodents of Madagascar, it survived to at least around 1536 BP based on radiocarbon dating. Little is known of its ecology, but it may have lived in burrows like its living relative and eaten some arid-adapted plants. Taxonomy ''Hypogeomys australis'' was described in 1903 by Guillaume Grandidier from subfossil material collected in the cave of Andrahomana in southeastern Madagascar. The ''Hypogeomys'' material was similar to the living '' Hypogeomys antimena'', but distinct enough for Grandidier to recognize it as a separate species, different in size and some morphological details. Grandidier described anot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
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 last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever 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 animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptoprocta Spelea
''Cryptoprocta spelea'', also known as the giant fossa, is an extinct species of carnivore from Madagascar in the family Eupleridae which is most closely related to the mongooses and includes all Malagasy carnivorans. It was first described in 1902, and in 1935 was recognized as a separate species from its closest relative, the living fossa (''Cryptoprocta ferox''). ''C. spelea'' was larger than the fossa, but otherwise similar. The two have not always been accepted as distinct species. When and how ''C. spelea'' became extinct is unknown; there is some anecdotal evidence, including reports of very large fossas, that there is more than one surviving species. The species is known from subfossil bones found in a variety of caves in northern, western, southern, and central Madagascar. In some sites, it occurs with remains of ''C. ferox'', but there is no evidence that the two lived in the same places at the same time. Living species of comparably sized, related carnivores ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subfossil Lemur
Subfossil lemurs are lemurs from Madagascar that are represented by recent (subfossil) remains dating from nearly 26,000 years ago to approximately 560 years ago (from the late Pleistocene until the Holocene). They include both extant and extinct species, although the term more frequently refers to the extinct giant lemurs. The diversity of subfossil lemur communities was greater than that of present-day lemur communities, ranging from as high as 20 or more species per location, compared with 10 to 12 species today. Extinct species are estimated to have ranged in size from slightly over to roughly . Even the subfossil remains of living species are larger and more robust than the skeletal remains of modern specimens. The subfossil sites found around most of the island demonstrate that most giant lemurs had wide distributions and that ranges of living species have contracted significantly since the arrival of humans. Despite their size, the giant lemurs shared m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microgale Macpheei
''Microgale macpheei'' is an extinct shrew tenrec from southeastern Madagascar. It is known only from two partial skulls found in Andrahomana cave, which radiocarbon dating of associated rodent remains suggests are about 3000 years old. It is the only known recently extinct tenrec. First described in 2007, it is most similar to the smaller '' Microgale brevicaudata'' of northern and western Madagascar. ''M. macpheei'' has a broad rostrum (front part of the skull) and, like ''M. brevicaudata'', lacks a diastema (gap) between the premolars. A number of details of tooth morphology are characteristic of ''M. macpheei''. Taxonomy Remains of shrew tenrecs (''Microgale'') were found during expeditions to the cave of Andrahomana in southeastern Madagascar, led by David Burney in 2000 and 2003.Goodman et al., 2007, p. 368 The ''Microgale'' material was described as a new species, ''M. macpheei'', in 2007 by Steven Goodman, Natalie Vasey, and Burney.Goodman et ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nesomys Narindaensis
''Nesomys narindaensis'' is an extinct rodent that lived in northwestern Madagascar. It is known from subfossil skull bones and isolated molars found in several sites during field work that started in 2001. First described in 2010, it is placed in the genus ''Nesomys'' together with three smaller living species, which may differ in some details of molar morphology. The presence of ''N. narindaensis'', a rare element in the local rodent fauna, suggests that the region was previously more humid. Taxonomy Remains of ''Nesomys narindaensis'' were found during fieldwork in northwestern Madagascar that started in 2001.Mein et al., 2010, p. 102 The species was described in a 2010 paper by Pierre Mein and colleagues, together with another extinct rodent, '' Brachytarsomys mahajambaensis''.Mein et al., 2010, p. 101 The specific name, ''narindaensis'', where one of the sites where the species has been found is located.Mein et al., 2010, p. 104 It is placed in the genus ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachytarsomys Mahajambaensis
''Brachytarsomys mahajambaensis'' is an extinct rodent from northwestern Madagascar. It is known from nine isolated molars found in several sites during fieldwork that started in 2001. First described in 2010, it is placed in the genus ''Brachytarsomys'' together with two larger living species, which may differ in some details of molar morphology. The presence of ''B. mahajambaensis'', a rare element in the local rodent fauna, suggests that the region was previously more humid. Taxonomy Remains of ''Brachytarsomys mahajambaensis'' were found during fieldwork in northwestern Madagascar that started in 2001.Mein et al., 2010, p. 102 The species was described in a 2010 paper by Pierre Mein and colleagues, together with another extinct rodent, ''Nesomys narindaensis''.Mein et al., 2010, p. 101 The specific name, ''mahajambaensis'', refers to Mahajamba Bay, which is close to the places where the species has been found.Mein et al., 2010, p. 103 It is placed in the g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name ''photosynthesis'', from the Greek ''phōs'' (), "light", and ''synthesis'' (), "putting together". Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crassulacean Acid Metabolism
Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but they open at night to collect carbon dioxide () and allow it to diffuse into the mesophyll cells. The is stored as four-carbon malic acid in vacuoles at night, and then in the daytime, the malate is transported to chloroplasts where it is converted back to , which is then used during photosynthesis. The pre-collected is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. This mechanism of acid metabolism was first discovered in plants of the family Crassulaceae. Historical background Observations relating to CAM were first made by de Saussure in 1804 in his ''Recherches Chimiques sur la Végétatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C4 Carbon Fixation
carbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960's discovery by Marshall Davidson Hatch and Charles Roger Slack that some plants, when supplied with 14, incorporate the 14C label into four-carbon molecules first. fixation is an addition to the ancestral and more common carbon fixation. The main carboxylating enzyme in photosynthesis is called RuBisCO, which catalyses two distinct reactions using either (carboxylation) or oxygen (oxygenation) as a substrate. The latter process, oxygenation, gives rise to the wasteful process of photorespiration. photosynthesis reduces photorespiration by concentrating around RuBisCO. To ensure that RuBisCO works in an environment where there is a lot of carbon dioxide and very little oxygen, leaves generally differentiate two partially isolated compartments called mesophyll cells and bundle-sheath cells. is initially fixed in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
δ13C
In geochemistry, paleoclimatology, and paleoceanography ''δ''13C (pronounced "delta c thirteen") is an isotopic signature, a measure of the ratio of stable isotopes 13C : 12C, reported in parts per thousand (per mil, ‰). The measure is also widely used in archaeology for the reconstruction of past diets, particularly to see if marine foods or certain types of plants were consumed The definition is, in per mil: :\delta \ce = \left( \frac - 1 \right) \times 1000 ‰ where the standard is an established reference material. ''δ''13C varies in time as a function of productivity, the signature of the inorganic source, organic carbon burial, and vegetation type. Biological processes preferentially take up the lower mass isotope through kinetic fractionation. However some abiotic processes do the same, methane from hydrothermal vents can be depleted by up to 50%. Reference standard The standard established for carbon-13 work was the Pee Dee Belemnite (PDB) and was based on a Cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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