|
Procoptodon Goliah
''Procoptodon'' is an extinct genus of giant short-faced ( sthenurine) kangaroos that lived in Australia during the Pleistocene Epoch. ''P. goliah'', the largest known kangaroo species that ever existed, stood at about . They weighed about . Other members of the genus were smaller, however; ''Procoptodon gilli'' was the smallest of all of the sthenurine kangaroos, standing approximately tall. The genus is derived from '' Simosthenurus'', making the latter genus paraphyletic. Description ''Procoptodon'' physiology was likely similar to that of the contemporary kangaroos; however, ''Procoptodon goliah'' was characterised by its large size. These sthenurines, or short-faced kangaroos, included species that were more than three times the size of the largest kangaroos living today. The largest, ''P. goliah'', was tall and weighed up to . These animals lived alongside modern species of kangaroos, but specialised on a diet of leaves from trees and shrubs. ''Procoptodon were'' large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owen produced a vast array of scientific work, but is probably best remembered today for coining the word '' Dinosauria'' (meaning "Terrible Reptile" or "Fearfully Great Reptile"). An outspoken critic of Charles Darwin's theory of evolution by natural selection, Owen agreed with Darwin that evolution occurred, but thought it was more complex than outlined in Darwin's ''On the Origin of Species''. Owen's approach to evolution can be considered to have anticipated the issues that have gained greater attention with the recent emergence of evolutionary developmental biology. Owen was the first president of the Microscopical Society of London in 1839 and edited many issues of its journal – then known as ''The Microscopic Journal''. Owen also c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procoptodon Goliah NT
''Procoptodon'' is an extinct genus of giant short-faced ( sthenurine) kangaroos that lived in Australia during the Pleistocene Epoch. ''P. goliah'', the largest known kangaroo species that ever existed, stood at about . They weighed about . Other members of the genus were smaller, however; ''Procoptodon gilli'' was the smallest of all of the sthenurine kangaroos, standing approximately tall. The genus is derived from '' Simosthenurus'', making the latter genus paraphyletic. Description ''Procoptodon'' physiology was likely similar to that of the contemporary kangaroos; however, ''Procoptodon goliah'' was characterised by its large size. These sthenurines, or short-faced kangaroos, included species that were more than three times the size of the largest kangaroos living today. The largest, ''P. goliah'', was tall and weighed up to . These animals lived alongside modern species of kangaroos, but specialised on a diet of leaves from trees and shrubs. ''Procoptodon were'' large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australian Megafauna
The term Australian megafauna refers to the megafauna in Australia during the Pleistocene Epoch. Most of these species became extinct during the latter half of the Pleistocene, and the roles of human and climatic factors in their extinction are contested. There are similarities between the prehistoric Australian megafauna and some mythical creatures from the Aboriginal Dreamtime. Causes of extinction Many modern researchers, including Tim Flannery, think that with the arrival of early Aboriginal Australians (around 70,000~65,000 years ago), hunting and the use of fire to manage their environment may have contributed to the extinction of the megafauna. Increased aridity during peak glaciation (about 18,000 years ago) may have also contributed, but most of the megafauna were already extinct by this time. Others, including Steve Wroe, note that records in the Australian Pleistocene are rare, and there is not enough data to definitively determine the time of extinction of many o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molar (tooth)
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (maxillary) and lower (mandib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chenopod
Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus ''Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making it the most species-rich lineage within its parent order, Caryophyllales. Description Vegetative characters Most species in the Amaranthaceae are annual or perennial herbs or subshrubs; others are shrubs; very few species are vines or trees. Some species are succulent. Many species have stems with thickened nodes. The wood of the perennial stem has a typical "anomalous" secondary growth; only in subfamily Polycnemoideae is secondary growth normal. The leaves are simple and mostly alternate, sometimes opposite. They never possess stipules. They are flat or terete, and their shape is extremely variable, with entire or toothed margins. In some species, the leaves are reduced to minute scales. In most cases, neither basal nor terminal aggrega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C4 Photosynthetic
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] |
Dental Crown
In dentistry, a crown most commonly refers to a dental cap, a type of dental restoration that completely caps or encircles a tooth or dental implant. A crown may be needed when a large cavity threatens the health of a tooth. A crown is typically bonded to the tooth by dental cement. They can be made from various materials, which are usually fabricated using ''indirect methods''. Crowns are used to improve the strength or appearance of teeth and to halt deterioration. While beneficial to dental health, the procedure and materials can be costly. The most common method of crowning a tooth involves taking a dental impression of a tooth prepared by a dentist, then fabricating the crown outside of the mouth. The crown can then be inserted at a subsequent dental appointment. This ''indirect method'' of tooth restoration allows use of strong restorative material requiring time-consuming fabrication under intense heat, such as casting metal or firing porcelain, that would not be possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicuspids
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered transitional teeth during chewing, or mastication. They have properties of both the canines, that lie anterior and molars that lie posterior, and so food can be transferred from the canines to the premolars and finally to the molars for grinding, instead of directly from the canines to the molars. Human anatomy The premolars in humans are the maxillary first premolar, maxillary second premolar, mandibular first premolar, and the mandibular second premolar. Premolar teeth by definition are permanent teeth distal to the canines, preceded by deciduous molars. Morphology There is always one large buccal cusp, especially so in the mandibular first premolar. The lower second p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Microwear
Dental microwear analysis is a method to infer diet and behavior in extinct animals, especially in fossil specimens. Typically, the patterns of pits and scratches on the occlusal or buccal surface of the enamel are compared with patterns observed in extant species to infer ecological information. Hard foods in particular can lead to distinctive patterns (although see below). Microwear can also be used for inferring behavior, especially those related to the non-masticatory use of teeth as 'tools'. Other uses include investigating weaning in past populations. Methods used to collect data initially involved a microscope and manually collecting information on individual microwear features, but software to automatically collect data have improved markedly in recent years. Potential issues and on-going debates * The role of phytolith Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Masseter
In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the most superficial and one of the strongest. Structure The masseter is a thick, somewhat quadrilateral muscle, consisting of three heads, superficial, deep and coronoid. The fibers of superficial and deep heads are continuous at their insertion. Superficial head The superficial head, the larger, arises by a thick, tendinous aponeurosis from the temporal process of the zygomatic bone, and from the anterior two-thirds of the inferior border of the zygomatic arch. Its fibers pass inferior and posterior, to be inserted into the angle of the mandible and inferior half of the lateral surface of the ramus of the mandible. Deep head The deep head is much smaller, and more muscular in texture. It arises from the posterior third of the lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
