Well, you're not doing too bad on anatomy. That is, you've got some sense of depth where muscles and tendons should actually go. You've got to work on perspective though. The car is at an entirely wrong angle, and the characters look like they're standing on invisible rocks or something. From the location of objects, it appears the ground should be more or less flat, but you've got the perspectives all wrong. Also, the taller character... what's up with the arms? It's like t-rex/midget forearms on massive biceps. The younger one looks pretty good for the most part, slight shrunken forearm for the one by his head. Fix that, and make his feet look like they're standing on the actual ground, and he'd be good to go.
Also, take a look at the tails. I see this from almost everyone doing furry art. They have tails starting right below the waistline or belt. That's off by quite a bit. Feel your own spine, follow it down to where it ends in your aptly named "tailbone" and realize just how far that is below your waist. Also note that, when standing, the bone is still going straight down. Now look at a dog. Unless they're holding their tail up high, the normal position is even LOWER than straight. Basically, just think about your character on four legs... and figure out where the tail attaches and at what angle.
