Mammal Evolution

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Evolution Of Mammals

Evolution of Mammals

Mammals have evolved from a group of reptiles called synapsids. These rose in the Pennsylvanian Period ( 310 million years, lasting about 35 million years ). By the Permian Period ( 275 million years lasting around 50 million years ), a branch called therapsids evolved. Over many million years, they evolved features that are found in mammals. A branch of the therapsids - the cynodonts - had many features of mammals, and it is believed that mammals evolved from this group.

Early mammals must have come about as a separate group at around 225 million years to 180 million years ago ( the Triassic Time Period ). There are many fossils that belong to such early mammals or cynodonts. But one cannot be sure on such things as many characteristics like mammary glands were not preserved.

By 180 million years ago ( The Jurassic Period ) mammals had certainly evolved. They were tiny rodent like animals. They remained quite small through the Cretaceous Period ( 130 million years to 65 million years ago ). Dinosaurs lived during these days.

The time of mammals came with the dying out of dinosaurs that occurred at around 65 million years ago. From then, mammals became the dominant land vertebrates. By the Oligocene Period's end, the modern mammal's families had come through ( 40 Million years to 26 million years ago ).

Many mammals became extinct at around the Pleistocene Epoch began at around 13/4 million years ago. This period brought about a major change in the climate of and may mammals went to their graves at this time - like the mammoths, sabre-toothed tigres. The main cause is due to climatic temperature, though some people think it was due to early man.

Many mammals have got extinct due to man's hunting and poaching. The blue buck of Africa is one such example of an animal killed. One does not even know if animals like Kuprey is alive or not. Many animals are on the verge of extinction.