1,2,3 = 2,3,4: accommodating the cladogram.
Feduccia
A
A
Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA. feduccia@bio.unc.edu
D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology; D005426:Flight, Animal