quarta-feira, 4 de novembro de 2009


Mammals -
* Mammals (Latin scientific Mammalia) are a class of vertebrate animals characterized by the presence of mammary glands in females which produce milk to feed the youngers , and the presence of fur or hair. Animals are homeothermic (ie, constant temperature, also known as "warm-blooded animals").
* The brain controls the body temperature and circulatory system, including the heart (four chambers). Mammals include 5416 species (including humans), distributed in about 1,200 genera, 152 families and 46 orders, according to the compendium published by Wilson and Reeder (2005). However new species are discovered each year, increasing that number, and by the end of 2007, the number reached 5558 species of mammals.
* The mammals are the actual descendants of synapsids, the first well-established group of amniotes that arose in the Upper Carboniferous.

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