Yep, all level 48, 58, 78 and 98 school-only pets have a chance of creating a hybrid when hatched with certain other school-only pets. My wizards have a couple: a Shadow Phoenix (Scarecrow/Phoenix hybrid) and a Magma Dragon (Bone Dragon/Efreet hybrid).
Central's Wiki lists them all out. Just go to the page for a school-only pet, and it will list the pet's information, including all possible hybrids that pet can produce in a hatch. For example, here is the page for the Forest Lord pet level 58 Life wizards earn..... http://www.wizard101central.com/wiki/Pet:Forest_Lord The possible hybrids are at the bottom of the right column of the page, under Forest Lord's derby talent pool.