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    I don't have any idea what the unicorn bit was about, but my point is
merely that if we were to be deprived of certain key bits of information,
i.e. the existance of volant paleognaths such as tinamous,
lithornithiforms, and volant outgroups, we would be helpless to use
phylogenetic bracketing to answer the question of whether ratites were
secondarily flightless; and perhaps because of the very poor record of
early birds a similar situation could exist in which secondarily
flightless dinosaurs could not be revealed as secondarily flightless by
phylogenetic means. Obviously this leaves only the functional approach.
    And it's not true that there is "no evidence" for secondary
flightlessness. The section in Predatory Dinosaurs provides a list of
evidences for secondary flightlessness. Are they unambiguous? The vast
majority you can put quite a few different spins on, and invoke predation,
tree climbing, or powered flight. But proponents of secondary
flightlessness do not need to demonstrate that features exist in the
skeleton of Velociraptor and other dinosaurs which could only be used for
flight. They merely need to demonstrate that there are enough features
which suggest strongly enough that these animals had a volant ancestry
that it is more likely than the alternative, i.e. the hypothesis that
flight evolved somewhere after Archaeopteryx split with Unenlagia.