Lyme disease is the leading vector-borne disease—meaning diseases that are transmitted to humans from another organism like a tick or mosquito—in North America and Europe.
Sep 22, 2023
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Trying to finish your homework while the big game is on TV? "Visual-movement" neurons in the front of your brain can help you stay focused, according to a new study from neuroscientists in the Perelman School of Medicine ...
Aug 9, 2023
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University of Queensland research has revealed features of early human brain development are mimicked in the brains of marsupials.
May 23, 2023
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The current outbreak of a highly contagious strain of H5N1 avian influenza has been called the worst in history. By January 2023, poultry farmers in the U.S. had slaughtered almost 60 million birds infected or at risk of ...
Apr 13, 2023
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"Don't poke the bear," they said. But that's exactly what a team of scientists have been doing to discover the secrets of blood clotting.
Apr 13, 2023
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The American Gastroenterological Association (AGA) has released new clinical guidance to help physicians and patients identify if unexplained digestive symptoms are due to alpha-gal syndrome, a food allergy that is caused ...
Mar 21, 2023
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You can easily picture yourself riding a bicycle across the sky even though that's not something that can actually happen. You can envision yourself doing something you've never done before—like water skiing—and maybe ...
Feb 23, 2023
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An eleven-year-old girl in Cambodia has died from bird flu, the country's first fatality from the virus in years, health authorities said.
Feb 23, 2023
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Bats are asymptomatic carriers of a multitude of viruses that are pathogenic to most other mammals. How has their immune system evolved to shield them from these pathogens?
Nov 28, 2022
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Researchers at Linköping University have identified in mice the cells in the blood vessels of the brain that are necessary for a fever reaction. The results have been published in Proceedings of the National Academy of Sciences ...
Oct 26, 2022
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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.
This text uses material from Wikipedia, licensed under CC BY-SA
