Yes and no.
Super Mario World 2: Yoshi's Island unused sprites
A little digging into the SMW2 ROM uncovers some very interesting sprites that, for one reason or another, did not make it into Yoshi's Island.
On the top-right are Shy Guys and a Tweeter from <a href="smas.shtml">Super Mario All-Stars[/url], and some odd-looking Bob-ombs above the green X's.
On the left side we can make out three more possible Yoshi transformations: Plane, Tree, and Mushroom. I'd guess the plane met its end at the hands of the helicopter, and if they were ever serious about the tree and the mushroom they eventually came to their senses and quickly scrapped them. If they actually made it into the game, here's our best guess at how they would be animated:
The SMW2 sprites shown above were not compressed.
Source:
http://themushroomkingdom.net/lostbytes.shtmlThe flared out version isn't there.