I was wondering how many people actually noticed this little detail that TRS threw into the game. (I noticed it the moment I learned what a Leviathan was.... basically a couple months ago)
In "The Developement of Evolve" thread, @MacMan posted about a sea-creature called the Leviathan, the Leviathan was, as MacMan put it:
Unfortunately it was scrapped, but not entirely. You can see a Leviathan, dead, beached, and partially eaten by reavers on "Weather Control". For those who don't know, this is what the Leviathan's concept art looks like:
And here is what it looks like on Weather Control:
As anyone could see, obviously it has been scaled down a bit and simplified but it's really cool that they would throw in this easter egg/reference back to the old ideas.