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Simplified phylogeny of Avialae (after Chiappe, 2002). Lineages with toothless taxa are in red. (A) Skull of Velociraptor. (B) Skull of Archaeopteryx lithographica. (C) Skull of Confuciusornis sanctus. (D) Comparison of the skulls ofC. sanctus and a pigeon (bottom). (E) Skull of Hesperornis regalis (after Marsh, 1880). (F) Ichthyornis dispar (after Marsh, 1883).
