Input (grade 13): 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.
Output (grade 11): 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.