What was one of the first birds that appeared during the Mesozoic period?

One of the first birds that appeared during the Mesozoic period was Archaeopteryx. This transitional species, which lived around 150 million years ago in the Late Jurassic, exhibited both avian and reptilian characteristics, such as feathers, wings, and a wishbone, alongside teeth and a long bony tail. Archaeopteryx is significant for illustrating the evolutionary link between dinosaurs and modern birds. Its discovery provided crucial evidence for the theory of evolution and the origins of flight in birds.