Archaeopteryx

When Archaeopteryx was described in 1861, it caused a sensation. With wings and feathers, it was considered the first bird, although now scientists don’t think it could fly that well. But unlike modern birds, it also had teeth and a bony tail. Discovered not long after Charles Darwin proposed the theory of evolution by means of natural selection, Archaeopteryx provided an example of evolution in action—a fossil that showed the transition between non-avian dinosaurs and birds.