Mammal-like reptile
old term for synapsids From Wikipedia, the free encyclopedia
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Mammal-like reptile is an old term for the therapsids: those synapsids which gave rise to the true mammals.
The term is both outmoded and a mistake, because mammals did not descend from reptiles. Both groups descended from early amniotes (egg-laying tetrapods), probably in the Lower or Middle Carboniferous.[1]
The precursors of reptiles are called sauropsids, and the precursors of mammals are called synapsids. The immediate ancestors of the mammals came from a group of therapsids called the cynodonts.[2][3]
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Mammals and reptiles
There are a number of characteristics which cannot be seen on fossils, but which are of great importance.
Mammals are distinguished from reptiles by fundamental differences in the development of the blood system.[4][5] These differences are such that it would be almost impossible for mammals to be derived from reptiles.
- "It is clearly quite impossible for the condition found in birds and modern reptiles to have arisen from that found in mammals or vice versa". Kermack.[5]6
This supports the division of amniotes into sauropsida and synapsida.
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References
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