Explain giving an example how the following provide evidences in favour of evolution in organisms. (i) Homologous organs (ii) Fossils

(Note: In the rationalized NCERT Class 10 Science textbook, the topic of Evolution has been omitted, and the chapter focuses solely on Heredity. However, based on the complete CBSE curriculum, the explanation is as follows:)

(i) Homologous Organs:

Homologous organs are organs in different organisms that share a similar basic structural design and developmental origin, but perform different functions. They provide evidence for evolution by showing that these organisms have descended from a common ancestor and adapted to different ecological niches.

• Example: The forelimbs of a human, the wing of a bird, and the foreleg of a horse. They all have the same basic bony structure (consisting of humerus, radius, ulna, carpals, and phalanges) but are modified to perform different functions like grasping, flying, and running respectively.

(ii) Fossils:

Fossils are the preserved remains, impressions, or traces of ancient organisms that lived millions of years ago. They provide direct, physical evidence of evolutionary history by showing the intermediate stages of modern-day organisms and documenting the existence of species that are now extinct.

Example: The fossil of Archaeopteryx* exhibits features of both reptiles (such as a long bony tail and teeth) and birds (such as feathers and wings). This transitional fossil provides strong evidence that birds evolved from reptilian ancestors.