Convergence of characters

Character convergence occurs when two species on different evolutionary trajectories evolve to possess the same character. For an example, consider the division of dinosaurs into the orders Saurischia (lizard-hipped) and Ornithischia (bird-hipped). Although birds evolved from dinosaurs, they derive from a suborder of saurischians, not ornithischians. The result is that

Converging characters (in addition to reversion) can greatly complicate character-based phylogeny, calling for more rigorous phylogenetic methods.