Hmm... Well I have some advice! Your dragons are good, their anatomy is is pretty well done, but their poses are flat. What do I mean by flat poses? Well none of any of the draws your showed had dynamic poses. They were all from the side and they were just kinda standing there. Try changing their stance a bit, maybe see them from a 3/4ths view rather than a simple side view. Draw them in motion, perhaps have them running or flying? Having them all stand in one pose makes the characters themselves look flat and soon they all start to look the same; even though they may be very different.
Here is a good example of some dynamic poses with a human figure:
http://th02.deviantart.net/fs70/PRE...__dynamic_poses_by_thethirdcartel-d5ghtvx.png
As you can see, even the standing ones have some different pizzazz to them. There are a ton of different poses you can try, and each would only increase your ability to draw! Since your characters are feral, look of images of say... a dog running, or maybe a big cat hunting. Then you can inference those poses and apply them to your own characters.
Drawing cartoony is no excuse to not draw dynamically.
Now, that being said. It is HARD. I still struggle to push myself and make all of the drawings I do dynamic. Even just simple sketches. And I wont sugar coat it, it'll be frustrating and make you want to throw your sketchpad at someone -don't do it, people don't seem to like it very much- but it will be rewarding in the long run. If I were to pick a time span of when I have started to make the most improvement in my art; it was when I started to draw things differently and from different angles.
Now as for your hyena drawing, the anatomy definitely needs some work.
http://www.interestingtopics.net/storage/picture20.jpg
Look at the hyena above, you see how it's hips are lower? And the front legs are a lot shorter than how you drew them. What I would suggest is to take the legs down a little and give your hyena some eat on it's bones. Hyenas have larger ribcages, and have a much rounder stomach. By fattening them up and moving the legs down a bit it would make it look far more realistic, but still have that cartoony appeal.
Now for the paws, you suffer from something I see a lot in canine artists; bubble pads.
http://farm2.static.flickr.com/1264/551742886_456f1b3536_b.jpg
Look at the paws here, you see how the pads of the feet are not that visible when they stand? While you can somewhat see them, the hyena is putting pressure on them so they have flattened out a little to allow it to walk.
The face is pretty good, I would look at more references of their faces though, since the head shape seems a bit off.
Over all, your art is pretty good! I do like how you drew the dragons, so adding some more expressive and dynamic poses will be awesome. Good luck with your future art and I hope this was helpful!