I like Padian and May's (1993) definition, not just because it appears to
have date priority(?) over all other clade definitions, but also because
it is "edgy" and current.
But what happens if Hell freezes over, and Martin, Feduccia et al. are
correct? Dinosauria would end up including all archosaurs and avicephalans,
and perhaps all of Sauria if Senter is right about where Longisquama goes.