I agree that this animal looks very sinister. I think you have gained more experience since starting art class, and it definitely shows in your work. But, here comes some critique, hopefully it doesn't sound harsh.
1) The tongue seems to be larger than it would in reality. If the piece you're creating is for the animal to look fierce and feral, than the tongue fits.
2) It also seems to be attached to the side of the mouth, rather than twisting from the middle and edging out of the mouth.
That's basically all I noticed that might be a little off. If you are able to work on the tongue and fix the minor flaws, I believe your drawing will be a success.