The living animals which possess the characteristics of two different groups of animals are known as connecting links. For example,
Lung fish: - Lung fish possesses the characters of both the fishes and amphibians. It resembles the fishes in having paired fins, gills and scales over body, on the other hand, it also have the ability to respire through lungs which is the characteristic property of amphibians. Thus lung fish acts as a connecting link between fish and amphibians. This suggests that in the past, amphibious organisms have developed from fishes.
Test Your Understanding and Answer These Questions:
- What is a connecting link?
- How can you prove that birds have evolved from reptiles?