"Archosaur": "Extinct reptiles
Well, they did include birds (in dinosaurs)... B-) However, write an irate letter to protest the use of "thecodonts", the inclusion of plesio- and ichthyosaurs and the exclusion of crocodiles.
The definition of Archosauria is AFAIK something like (Crocodylia + Neornithes).
But as HP Tom Holtz said, normal dictionaries are never exact on such terms. The Duden (the most authoritative German dictionary) even mandates writing Archäopteryx instead of *Archaeopteryx* (and gives a plural form, -pteryges), not knowing that scientific names are not subject to national orthographies!!! Fortunately, most people don't follow this, even in popular writings, but it occurs sometimes.
For joy, lack of time and forgetfulness I forgot to write that I am now an SVP student member! Great to see _lots_ of you out there in the address directory! (I'm only the 3rd Austrian member; there are 20 times as many Germans in the SVP, while Germany has 10 times as many inhabitants...)