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28 de dez. de 2020 · Learn how mammals are distinguished from other vertebrates by traits such as hair, mammary glands, single-boned lower jaws, and four-chambered hearts. Explore the diversity and adaptations of mammals with examples and illustrations.
- Bob Strauss
- Overview
- Diversity
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An animal is considered a mammal if it can produce milk. Other features unique to mammals include hair or fur (chemically different from hairlike structures on non-mammals); the malleus, incus, and stapes in the ear; and a diaphragm separating the heart and lungs from the abdomen. Also, mammals lack nuclei in mature red blood cells.
How many species of mammals are there?
It is estimated that there are more than 5,500 living mammal species. Mammals are incredibly diverse and can be found in every major habitat.
What is the biggest mammal?
The biggest living mammal—indeed, the largest animal ever—is the blue whale. It can be as heavy as 180 metric tons (200 short tons) and reach a length of more than 30 metres (98 feet).
Did mammals and dinosaurs exist at the same time?
The evolution of the class Mammalia has produced tremendous diversity in form and habit. Living kinds range in size from a bat weighing less than a gram and tiny shrews weighing but a few grams to the largest animal that has ever lived, the blue whale, which reaches a length of more than 30 metres (100 feet) and a weight of 180 metric tons (nearly 200 short [U.S.] tons). Every major habitat has been exploited by mammals that swim, fly, run, burrow, glide, or climb.
Britannica Quiz
Moms of the Animal Kingdom Quiz
There are more than 5,500 species of living mammals, arranged in about 125 families and as many as 27–29 orders (familial and ordinal groupings sometimes vary among authorities). The rodents (order Rodentia) are the most numerous of existing mammals, in both number of species and number of individuals, and are one of the most diverse of living lineages. In contrast, the order Tubulidentata is represented by a single living species, the aardvark. The Uranotheria (elephants and their kin) and Perissodactyla (horses, rhinoceroses, and their kin) are examples of orders in which far greater diversity occurred in the late Paleogene and Neogene periods (about 30 million to about 3 million years ago) than today.
The greatest present-day diversity is seen in continental tropical regions, although members of the class Mammalia live on (or in seas adjacent to) all major landmasses. Mammals can also be found on many oceanic islands, which are principally, but by no means exclusively, inhabited by bats. Major regional faunas can be identified; these resulted in large part from evolution in comparative isolation of stocks of early mammals that reached these areas. South America (the Neotropics), for example, was separated from North America (the Nearctic) from about 65 million to 2.5 million years ago. Mammalian groups that had reached South America before the break between the continents, or some that “island-hopped” after the break, evolved independently from relatives that remained in North America. Some of the latter became extinct as the result of competition with more advanced groups, whereas those in South America flourished, some radiating to the extent that they have successfully competed with invaders since the rejoining of the two continents. Australia provides a parallel case of early isolation and adaptive radiation of mammals (specifically the monotremes and marsupials), although it differs in that Australia was not later connected to any other landmass. The placental mammals that reached Australia (rodents and bats) evidently did so by island-hopping long after the adaptive radiation of the mammals isolated early on.
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Mammals are vertebrates that feed their young with milk, have hair, and a hinged lower jaw. Learn about the diversity, evolution, and classification of mammals, and see examples of living and extinct species.
22 de nov. de 2023 · Learn what makes a mammal a mammal, with examples of different orders and species. Find out the evolutionary history, interesting facts, and examples of mammals and non-mammals.
9 de fev. de 2017 · Learn what makes a mammal a mammal with this comprehensive guide. Discover the shared and unique features of all mammals, and see examples of different types of mammals.
A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia ( / məˈmeɪli.ə / ). Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a neocortex region of the brain, fur or hair, and three middle ear bones.
Mammals are warm-blooded vertebrates with four limbs, hair, and milk-secreting glands. They range in size, shape, and behavior, and include bats, whales, primates, and rodents.
28 de ago. de 2015 · All mammals have hair of some sort, as well as mammary glands. In female mammals, the mammary glands produce milk that they use to feed their young . Mammals are also warm-blooded , which means they regulate their own body temperature via a region in the brain called the neocortex.
