Birds are the only direct descendants of theropod dinosaurs. In an evolutionary sense, they are the closest thing we have to living dinosaurs. Theropods, which include Tyrannosaurus RexVelociraptor and other dinosaurs were a diverse group of bipedal carnivores.
However, not all theropods were terrifying giants. Some were quite small and probably covered in feathers, leading scientists to believe that these feathered theropods are the ancestors of our modern birds.
The way theropod dinosaurs gradually evolved into birds shows the adaptability of life and natural selection. The fossil record shows a gradual evolution from theropods towards the birds we see today.
Key changes included the development of a wishbone, the fusion of bones to form a stronger, lighter skeleton, and the evolution of feathers from simple filaments to complex structures capable of flight.
The defining traits of modern birds—feathers, a toothless beak, and laying hard-shelled eggs—were present in some form in their dinosaur ancestors.
In fact, Archeopteryx, often considered the first bird, provides a snapshot of this transition. With its mix of avian and reptilian characteristics, it helps us visualize the intermediate stages of this evolutionary journey.