I really think you're on to something with the otter and the rhino. the otter's pose is a little akward. i don't really know what emotion he's got with that pose. but I know you just had to get it done for class. Like all character design, a little more development would make it shine!
That Rhino is excellent. The birds are a nice touch.
These are pretty nice. Good job.
Love the Rhino, Ron. Your stuff always has personality. I know you were auditing the class, but did you do a final for character design? If you did you should post them.