How do similarities in the bones of humans dolphins horses and birds provide evidence evolution?

The presence of homologous structures in the bones of humans, dolphins, horses, and birds provides evidence of evolution through common ancestry. Homologous structures are anatomical structures that share a common evolutionary origin, indicating that these species may have evolved from a common ancestor.

* Humans and dolphins. Humans and dolphins both have the same basic skeletal structure, including a backbone (vertebrae), limb bones (humerus, femur, etc.) and skulls with similar features such as jaws, teeth, and eye sockets.

* Horses and birds. Horses and birds also share homologous structures, despite their vastly different forms. They both possess limb bones that homologous to each other, for example, their forelimbs have a humerus, radius and ulna, while their hindlimbs have a femur, tibia and fibula. Additionally, birds' wings demonstrate striking similarities to the forelimbs of other vertebrates, even though they serve different functions.

These similarities in bone structure, combined with evidence from other fields such as DNA comparison and paleontology, suggest that these species shared a common ancestor in their evolutionary history, and the diverged in course of time leading to their diverse adaptations.