There was a Rhino in the ASM game, He was a literal rhino who became a Man-Rhino thing and got semi intelligence.
Though I can see the def appeal of Rhino for a movie, since really he's probably one the easier "Known Foes" that they can change to suit their whims.
I get them making Rhino a animal-powered mutant like the Lizard. Between Lizard and Spider-Man's powers, plus looming Osborn as the villain, they're probably gonna tie all the enemies Spidey faces together as coming from this one source. The lesser villains all get their powers from a serum that grants the evolved abilities of various animals, while Osborn (if they go the Ultimate Green Goblin route) gets the evolved abilities of himself.