Like modern birds , Confuciusornis had a toothless beak , but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed . This shows that the loss of teeth occurred more than once , in Confuciusornis and in ancestors of modern birds . Like modern birds , Confuciusornis had a toothless beak , but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed , indicating that the loss of teeth occurred convergently in Confuciusornis and living birds .