Prehistoric Mammal Biology

The first prehistoric mammal appeared about 225 million years ago. It was a small and nocturnal creature living in a world dominated by large dinosaur carnivores. These mammals of the night were insectivores.

Following the extinction of the dinosaurs 66 million years ago, mammals gradually became the dominant animals on earth. They took over the roles of the medium to larger sized animals in the ecosystem.

Prehistoric mammals are similar to modern day mammals in a number of ways. They are vertebrates with backbones. They have lungs for respiration. They possess a neocortex – a specialized area in the brain that only mammals have. Prehistoric mammals have hair. Most also give birth to live baby mammals. They are also warm-blooded.


Mammals belong to the phylum Chordata. They are vertebrates and belong to the class Mammalia. There are many subgroups within this class. They include a wide range of animals from aquatic whales to flying bats to a wide range of terrestrial animals.


Mammals can be found all over the planet. The many different mammal species have adapted to terrestrial, aquatic, arboreal and aerial environments. They can be found in a wide range of climatic extremes – from ocean depths, to polar environments, to tropical rainforests and to arid deserts.

Prehistoric Mammals and Humans

The evolution of mammals has been affected by the world’s climate. The extinction of the dinosaurs and rise of the mammals began 66 million years ago. A major extinction event modified the earth’s climate and eliminated the dinosaurs. This was followed by a smaller extinction event 34 million years ago which lead to the extinction of the larger mammals. Those that survived have become the modern mammals of today.

Today human societies continue to modify habitats or hunt some mammal species to extinction. Mammals however remain an important food and energy source for human societies.

Improving Your Reading and Thinking Skills

Think for a few moments. Try to recall the major ideas in this article. When you are done, click the box below for a list of main ideas.


How did you do? With practice, you should be able to identify many of the major ideas. You may even discover some important ideas that aren’t listed.


Prehistoric Life, BBC.

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3 comments on "Prehistoric Animals: Prehistoric Mammals"

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Ronand Abella

The mamal is following the dinosaur for 66milloon ago.

Webster Gabiana


Webster Gabiana

the firs mammal appeared about 225