Oh yeah, the thread I forgot replying to...
Estelle Bourdon's prophaetornithid studies look as if the tropicbirds could make a good missing link - very autapomorphic, but apart from that they look as if they'd link waders to the stork-albatross-and-whatnot group.
One word: Metornithes.
(David: I noted that Estelle's thesis has some nomina nuda. A few of them have since been resolved. Is she planning to describe the others anytime soon?
No idea. She's no longer here, she's now doing a postdoc with Joel Cracraft.