Do you have any idea which were the first animals with warm blood? Let’s know about the fact in detail. The ability to control the body temperature is a considerable advantage to an animal. Even today, reptiles are cold blooded. In practice, this means that their body temperature corresponds with the temperature of the surrounding environment.
Now, the efficiency of an animal‘s body functions is very dependent on its temperature. This means that as the air temperature falls, the animal’s body temperature falls and its functions become more and more sluggish. Thus, reptiles survive perfectly well in warm climates, and even in cooler climates they manage by hibernating during the winter months.
First animals with warm blood
But cold blooded land animals cannot survive in the very cold regions of the Earth. You can see, then that if an animal has the ability to control its body temperature it has a considerable advantage over the reptiles in its adaptability to cold climates. It does mean, however, that in cooler places, animals must have their bodies insulated to prevent loss of heat.
This can be achieved by extra layers of fat, hair or fur in the case of mammals, and features in the case of birds. The ability to control body temperature may have evolved separately on two occasions. It is possible that a group of primitive reptiles may have been partly warm blooded and probably the dinosaurs could control their body temperature to some extent.
An animal with warm blood has a very high metabolic rate, as the speed of its body processes is known. But this in turn means that their cells, which make up the bodies of all living things, require more oxygen or they may be damaged.
Together with warm bloodedness, then, the blood supply carrying oxygen around the body must be made more efficient. There must be more blood vessels in the bones. It is interesting to note the bones of dinosaurs have almost as many pores as those of modern mammals.
In late Jurassic times (about 150 million years ago), an animal existed which has great importance in the development of life on Earth. This creature is known as Archaeopteryx; we expect that you have heard of it. It seems to be exactly intermediate between a bird and a reptile.
It had some feathers and could probably fly, although not very well. In order to be efficient enough to fly it must have been warm blooded. But its skeleton is more like that of certain dinosaurs, and rather than a bill, its jaws were armed with small teeth. This first bird probably developed from some of the reptiles that leapt from tree to tree.
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