Wall Of Mythic Rares
I found an interesting article on the Wizards main site, in the Magic Arcana section. The article looks at the, so called, ‘Wall Of Mythic Rares’ used by R&D to aid the development of the Mythic Rares in a set.
In this article they talk about this in relation to Zendikar – http://www.wizards.com/magic/magazine/article.aspx?x=mtg/daily/arcana/664
Specifically, for a card originally titled: Fire Dog Dinosaur.
They then do this with another card in Zendikar , in a later article – http://www.wizards.com/magic/magazine/article.aspx?x=mtg/daily/arcana/688&dcmp=ilc-mtgrss
This card was originally called, Loruthos, the Deeplord.