News tagged with mammals
Thousands of shellfish found dead in Peru
Thousands of crustaceans were found dead off the coast of Lima following the mystery mass death of dolphins and pelicans, the Peruvian Navy said Friday.
May 26, 2012 |
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Newly discovered sensory organ in the chin of baleen whales allows them to be world's largest hunters
Lunge feeding in rorqual whales (a group that includes blue, humpback and fin whales) is unique among mammals, but details of how it works have remained elusive. Now, scientists from the Smithsonian Institution ...
May 23, 2012 |
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The living fossils of brain evolution
(Phys.org) -- In the course of its evolution, the architecture of the mouse brain may have barely changed. Similar to the tiny ancestors of modern mammals that lived about 80 million years ago, nerve cells ...
May 23, 2012 |
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Seeing color traced back to genetic mutations
From the inside of our heads, it feels as if colors are intrinsic aspects of the outside world and our eyes are beautifully designed to see them. But we humans are merely sampling the possible ways of sensing the spectrum ...
May 21, 2012 |
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Toxic mercury, accumulating in the Arctic, springs from a hidden source
(Phys.org) -- Environmental scientists at Harvard have discovered that the Arctic accumulation of mercury, a toxic element, is caused by both atmospheric forces and the flow of circumpolar rivers that carry ...
Space & Earth / Earth Sciences
May 21, 2012 |
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Study highlights new mammal species for promoting conservation fundraising
Images of tigers and elephants are among the most common threatened mammals used by conservation organisations as ‘flagships’ to promote fundraising – but new research led by the University ...
May 17, 2012 |
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Elephant seal tracking reveals hidden lives of deep-diving animals
Researchers at the University of California, Santa Cruz, who pioneered the use of satellite tags to monitor the migrations of elephant seals have compiled one of the largest datasets available for any marine mammal species, ...
May 15, 2012 |
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Nearly one-tenth of hemisphere's mammals unlikely to outrun climate change: study
A safe haven could be out of reach for 9 percent of the Western Hemisphere's mammals, and as much as 40 percent in certain regions, because the animals just won't move swiftly enough to outpace climate change. ...
May 14, 2012 |
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Living longer -- variability in infection-fighting genes can be a boon for male survival
Females of mammals (including humans) tend to outlive males, a circumstance that is usually attributed to males´ more aggressive and hence energy-depleting behaviour, especially when they compete for females. This might ...
May 11, 2012 |
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Navy study: Sonar, blasts might hurt more sea life
(AP) -- The U.S. Navy may hurt more dolphins and whales by using sonar and explosives in Hawaii and California under a more thorough analysis that reflects new research and covers naval activities in a wider ...
May 11, 2012 |
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Evolution may explain 'Runner's high,' study says
(HealthDay) -- The pleasurable feeling known as "runner's high" that's triggered by aerobic exercise may have played a role in the evolution of humans' ability to run long distances, a new study suggests.
May 09, 2012 |
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Northern California fishermen free entangled whale
(AP) -- Crab fisherman Mark Anello noticed something odd near his boat off the Northern California coast: three buoys floating nearby were moving. Motoring closer he saw a gray whale tangled in a large fishing ...
May 06, 2012 |
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New study shows early North Americans lived with extinct giant beasts
(Phys.org) -- A new University of Florida study that determined the age of skeletal remains provides evidence humans reached the Western Hemisphere during the last ice age and lived alongside giant extinct mammals.
Other Sciences / Archaeology & Fossils
May 03, 2012 |
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Scientists discover way to detect low-level exposure to seafood toxin in marine animals
(Phys.org) -- NOAA scientists and their colleagues have discovered a biological marker in the blood of laboratory zebrafish and marine mammals that shows when they have been repeatedly exposed to low levels of domoic acid, ...
May 03, 2012 |
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Japan 'Cove' town plans dolphin park
The dolphin-hunting Japanese town of Taiji, made infamous by the Oscar-winning documentary "The Cove", plans to open a marine mammal park where visitors can swim with the creatures, a media report said.
May 01, 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.
