Well Ichthyosaur is a dinosaur fish which means 'fish-lizard' in ancient Greek. ichthy is the fish part of that. So it's fish-something. I think it's the thing living in the water.
As for the password. Hmmm, what parts of the document haven't we used yet?
-There's the repeated text we haven't found a reason for why it repeats.
-there's the odd shape that the words take when you put them all together. Is it a key? a grail?
-There's the roman numerals, although I don't see that being a password.