While I didn't find the article that I personally seen, I did find this one Lizard Evolution on the Quick at Jeremy Shere

Which takes place in about 30 years.

There is also this article, which seems to be on par of what I have read, http://www.dinosauria.com/jdp/evol/lizard.html


While yes, the Zora could handle the monsters that were in the water AT THE TIME, larger quantity of water could have made it so that the monsters were far greater than any Zora to deal with. Which maybe speculative, but very appropriate all things considered.