Lee,
The question regarding Campagnolo MTB derailleurs having evolved (morphed) from the road components sent me searching for an interesting URL I stumbled across several months back. While I cannot recall exactly where, I vaguely remember that it might have been imbedded in an eBay advert.
The site owner is Andy Smith in the UK. I do not know the gentleman and cannot vouchsafe the accuracy of his Campy MTB 'timeline'. His site seems fairly comprehensive and his methodical approach to presenting it does instill confidence.
It can be found at:
http://www--ipg.umds.ac.uk/
Mr. Smiths email address: Andy@ADSmith.org.uk
Hope this clears up the conundrum, or at least completely covers a chasm in the catalogue of our collective Campy consciousness.
Ciao,
Carlo Carr