Páginas: 4 (811 palabras) Publicado: 10 de abril de 2010
Reptiles are vertebrates. It is estimated that for about 310 million years descended from amphibians, but not modern amphibians today but other amphibians that lived on earth at that time. With thepassage of time mammals and birds arose from reptiles .

The seven thousand species of reptiles living today are classified into four basic groups. These groups are:


Lizardsand Snakes



Mammals are vertebrates like amphibians, reptiles, birds and fish. They differ from these others by having hairs on the body surface. In most mammals,but not all females have breasts which feed their young.
The mammals are descended from reptiles. There appears not much because mammals arose about 195 million ago years. Although it ispossible that the two branches have separated much earlier than that because these reptiles were descended from reptiles today. At that time the reptiles ruled the world, and we were small shrews. With thepassage of time, each group evolved in different directions, they turned us tinier and larger.

The 4.500 to 5.000 different species of mammals living today are discussed in groups. These arebased on similarities and differences between species. This occurs due to evolution or lineage relationship between them.

Squirrels, beavers, porcupines, mice
Armadillos, sloths, anteatersWhales, Dolphins
Horses, Rhinos, Tapirs
Kangaroos, koalas, possums
Pork Homiguero
Deer, Cattle, Giraffes
Rabbits, Hares, Spades
Hedgehogs, shrews, Topo
Cats,Dogs, Bears, Seals
Lemurs, Apes, Humans
Lemurs Gliders
Bats, Vampires
Tree shrew
Elephant Shrews
Platypus, echidna Nadiok


Amphibians were thefirst vertebrate animals to adapt to a semi-terrestrial life. It is estimated that emerged from the fish for about 360 million years. With the passage of time, they developed the reptiles that gave...
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