First Look at Grimlock's Dino Mode?

An image posted by JoBlo might be the first look at Grimlock's dinobot alt mode. In the picture it seems Optimus Prime is riding Grimlock like a horse while holding a sword and shield. The image, assuming inspired by movie plans, does look pretty awesome. The source is unknown so unable to confirm if its officially related to Transformers: Age of Extinction or just creative fan art. Thanks to Feris O. for the heads-up.