Wow. One heck of a question Leon.
I can easily get lost in imagination with this thought.
Check this out:
http://www.environment.gov.au/soe/1996/publications/technical/pubs/plesiosaurs.pdf
Interesting paper on the past 100 million years.
I think though that evolution beyond our age of being can no longer evolve too far physically further due to naturre but by synthetic manipulation.
