What are mammals?
Mammals are a class (i.e. group) of animals that are characterised by several features, which together make them distinct from other living things.
These features are:
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The production of milk for their offspring. This is produced by modified sweat glands or mammary glands (hence the name mammals!)
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The presence of sweat glands. These help the warm-blooded mammals to keep cool.
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At least some hair or fur during part of their life. Even dolphins have some facial hair when first born.
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Three middle ear bones, known as the stirrup, anvil and hammer. Before mammals evolved these bones were part of the jaw.
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A single lower jaw bone.
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A diaphragm, which is a sheet of muscle that separates the lungs and heart from the abdomen with the intestines, liver, kidneys etc.
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Heart with only one main artery that curves to the left.

