News tagged with mammals
H1N1 discovered in marine mammals
Scientists at the University of California, Davis, detected the H1N1 (2009) virus in free-ranging northern elephant seals off the central California coast a year after the human pandemic began, according ...
Diseases, Conditions, Syndromes
May 15, 2013 |
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How rats see things
The image of an object, when projected into the eyes, may take on the most diverse shapes depending on the chosen point of view, as this can change its distance, perspective and so on, yet generally we have no difficulty ...
Neuroscience
Apr 04, 2013 |
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How to mend a broken heart: Advances in parthenogenic stem cells
Parthenogenesis is a form of asexual reproduction during which unfertilized eggs begin to develop as if they had been fertilized. It occurs naturally in many plants and a few invertebrate (some bees, scorpions, parasitic ...
Medical research
Feb 22, 2013 |
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Scientists discover how animals taste, and avoid, high salt concentrations
Researchers have discovered how the tongue detects high concentrations of salt, the first step in a salt-avoiding behavior common to most mammals. The findings could serve as a springboard for the development of taste modulators ...
Health
Feb 13, 2013 |
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Lack of key enzyme in the metabolism of folic acid leads to birth defects
Researchers at The University of Texas at Austin have discovered that the lack of a critical enzyme in the folic acid metabolic pathway leads to neural tube birth defects in developing embryos.
Medical research
Jan 17, 2013 |
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New treatment may relieve chronic shortness of breath
People experiencing chronic shortness of breath may soon have a new way to help alleviate their discomfort, according to a Penn State College of Medicine pulmonology researcher.
Diseases, Conditions, Syndromes
Dec 19, 2012 |
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Antibiotics based on a new principle may defeat MRSA
(Medical Xpress)—Scientists at Karolinska Institutet in Sweden have presented a new principle for fighting bacterial infections, in other words, a new type of antibiotic, in the FASEB Journal. The new antibiotic mechan ...
Medical research
Dec 18, 2012 |
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Insight into DNA reprogramming during egg and sperm cell development
Scientists at the Babraham Institute have gained a new understanding of when and how the DNA in developing egg and sperm cells is 'reset', in preparation for making a new embryo. It is well known that small chemical groups ...
Genetics
Dec 06, 2012 |
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Could high insulin make you fat? Mouse study says yes
When we eat too much, obesity may develop as a result of chronically high insulin levels, not the other way around. That's according to new evidence in mice reported in the December 4th Cell Metabolism, a Cell ...
Medical research
Dec 04, 2012 |
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Migratory birds can spread haemorrhagic fever
A type of haemorrhagic fever that is prevalent in Africa, Asia, and the Balkans has begun to spread to new areas in southern Europe. Now Swedish researchers have shown that migratory birds carrying ticks are the possible ...
Diseases, Conditions, Syndromes
Oct 23, 2012 |
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Researchers identify lynchpin to activating brown fat cells
(Medical Xpress)—Researchers at the University of California, San Francisco (UCSF) have identified the lynchpin that activates brown fat cells, which burn fat molecules instead of storing them, making them ...
Medical research
Oct 19, 2012 |
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Bird flu debate: Should H5N1 experiments resume?
Virologists making mutated versions of the H5N1 bird flu halted their research in January after a U.S. government advisory panel suggested that their work, though well-intentioned, had the potential to endanger the public.
Medical research
Oct 13, 2012 |
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Scientists identify mammal model of bladder regeneration
While it is well known that starfish, zebrafish and salamanders can re-grow damaged limbs, scientists understand very little about the regenerative capabilities of mammals. Now, researchers at Wake Forest Baptist Medical ...
Medical research
Oct 12, 2012 |
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A mammal lung, in 3-D: Researchers create model of mysterious region
(Medical Xpress)—Amidst the extraordinarily dense network of pathways in a mammal lung is a common destination. There, any road leads to a cul-de-sac of sorts called the pulmonary acinus. This place looks ...
Medical research
Oct 02, 2012 |
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Study discovers first real indicator of longevity in mammals
A team of researchers from the Spanish National Cancer Research Centre (CNIO), headed by CNIO Director María Blasco, has demonstrated in a pioneering study on mammals that longevity is defined at a molecular level by the ...
Medical research
Sep 27, 2012 |
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Mammal
Mammals (formally Mammalia) are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.
Mammals are divided into three main categories depending how they are born. These categories are, monotremes, marsupials and placentals. Except for the five species of monotremes (which lay eggs), all mammal species give birth to live young. Most mammals also possess specialized teeth, and the largest group of mammals, the placentals, use a placenta during gestation. The mammalian brain regulates endothermic and circulatory systems, including a four-chambered heart.
There are approximately 5,400 species of mammals, distributed in about 1,200 genera, 153 families, and 29 orders (though this varies by classification scheme). Mammals range in size from the 30–40-millimetre (1.2–1.6 in) Bumblebee Bat to the 33-metre (110 ft) Blue Whale.
Mammals are divided into two subclasses, the prototheria, which includes the oviparous monotremes, and the theria, which includes the placentals and live-bearing marsupials. Most mammals, including the six largest orders, belong to the placental group. The three largest orders, in descending order, are Rodentia (mice, rats, and other small, gnawing mammals), Chiroptera (bats), and Soricomorpha (shrews, moles and solenodons). The next three largest orders include the Carnivora (dogs, cats, weasels, bears, seals, and their relatives), the Cetartiodactyla (including the even-toed hoofed mammals and the whales) and the Primates to which the human species belongs. The relative size of these latter three orders differs according to the classification scheme and definitions used by various authors.
Phylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals). This means that some extinct groups of "mammals" are not members of the crown group Mammalia, even though most of them have all the characteristics that traditionally would have classified them as mammals. These "mammals" are now usually placed in the unranked clade Mammaliaformes.
The mammalian line of descent diverged from an amniote line at the end of the Carboniferous period. One line of amniotes would lead to reptiles, while the other would lead to synapsids, including mammals. The first true mammals appeared in the Triassic period. Modern mammalian orders appeared in the Palaeocene and Eocene epochs of the Palaeogene period.
For more information about Mammal, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
