i have two favorite dinos, im a bit of a Dino Fiend 
http://i.imgur.com/ENfSE.jpg
On the left is an Pockmarked Scamosaurus, on the right is a Popeyed Coprophiliasaurus. They were often found together in the wild, as they shared a symbiotic relationship - the Coprophiliasaurus fed on the nutritious chitin that the Scamosaurus secreted from its blister-like epidermal pouches. Because of this, Scamosaurii evolved to produce more and more of this chitin, to the point that when no Coprophiliasaurii were to be found in their immediate surroardings, their pores often clogged.
http://i.imgur.com/ENfSE.jpg
On the left is an Pockmarked Scamosaurus, on the right is a Popeyed Coprophiliasaurus. They were often found together in the wild, as they shared a symbiotic relationship - the Coprophiliasaurus fed on the nutritious chitin that the Scamosaurus secreted from its blister-like epidermal pouches. Because of this, Scamosaurii evolved to produce more and more of this chitin, to the point that when no Coprophiliasaurii were to be found in their immediate surroardings, their pores often clogged.