Brain size riddle solved as humans exceed evolutionary trend
The largest animals do not have proportionally bigger brains—with humans bucking this trend—a study published in Nature Ecology & Evolution has revealed.
The largest animals do not have proportionally bigger brains—with humans bucking this trend—a study published in Nature Ecology & Evolution has revealed.
Plants & Animals
Jul 8, 2024
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Giant lizards called heath goannas could save Australian sheep farmers millions of dollars a year by keeping blowfly numbers down—and must be prioritized in conservation schemes to boost native wildlife, say researchers.
Plants & Animals
Jun 25, 2024
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Being nursed by a single parent could be an evolutionary strategy to curb the spread of harmful microbes in mammals, according to a novel theory developed by mathematicians.
Plants & Animals
Jun 27, 2024
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Yunnan, China is a biodiversity hotspot, with many new reptile species discovered in the region in recent years. It is also where a research team from China found a new species of medium-sized venomous snake, known as a mountain ...
Plants & Animals
Jun 11, 2024
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Cave lions lived in what is now Italy around 660,000 to 610,000 years ago. This is confirmed by a metatarsal bone from the Notarchirico site near Venosa in the Basilicata region, which was discovered during a re-examination ...
Paleontology & Fossils
Jun 24, 2024
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Invasive alien species (IAS) explored in a CABI-published book pose the biggest threat to biodiversity, crop and/or livestock production, human and/or animal health, and economic development in the Caribbean.
Plants & Animals
Jun 12, 2024
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When people talk about animal parents, often they are thinking about mothers. But the role of fathers in the animal kingdom is fascinating—and can tell us a lot about ourselves.
Evolution
Jul 3, 2024
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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