Mammalia  

Presently one of the most successful animals are classed as Mammalia. They inhabit all parts of the earth, including the sea and barren lands. They range in sizes from a few centimeters and weighing a few grams (e.g. mice)  to 30 meters and up to a hundred tons (e.g. whales) but all members are warm-blooded vertebrates (having a spinal column) with a relatively well-developed brain. Some or all parts of their body are covered by hair and most members of the class have four limbs, which evolved into walking, handling, flying and swimming instruments with the exceptions of very few having only two or none (sea mammals). Another distinguishing trait is the sexual breeding through copulation by male and females and  the parental care they give their young, nourishing them with milk, produced in the female mammary glands, which gave that class its name (except monotremes).

Mammals appeared in the later Mesozoic era (225 - 65 millions ago) and are believed descendants of mammal-like reptiles, called Theriodontia, which lived in the earlier period of this era. Those animals somehow survived the mass extinction of 65 million years ago and adapted better to the changing world as did the famous dinosaurs and other reptilians, which were the dominant animals till then. Mammals started then to fill the abandoned niches left by the reptiles and expanded their geopgraphical ranges and split into multiple species by adaptive radiation. 

The class is presently divided in 3 sub-classes, with one the Monotremes, which are egg-laying mammals with only 6 species left (e.g. spiny anteater) and only found in Australia and surrounding islands. The Marsupials is another sub-class with 272 species, most of them inhabit also those parts of the world, with a few (e.g. opossums) found also on the American continent. The third one are the Placentals, which comprises the majority of the over 4600 species of mammals worldwide. They are found on all continents but  with only a few species living in Australia (rats and bats) and have 18 major orders.

18 orders of placental mammals

Other sub-classes and orders existed before but became extinct over period of times. Presently, although considered the most advanced of all animals, some members of this class are also in danger of extinction, for the most part because of the action of the most recent and most powerful mammal, called Man.

On the individual pages you will find a list of the species at the end. It gives you the common name of the mammals, scientific names and where it can be found and at which altitudes. As example is shown the condor. Locations could be Galapagos (G), Coast (C), Andes (M) and Amazon (A) and altitudes are given in meters.

People, who are not so much interested in explications but like to see and enjoy pictures of mammals, should check out the animal.section of our Ecuador-Images.net.