Today I got thinking about Colo Colo's head. The first set of drawings (below) I was experimenting with head style, throwing out beak shapes as they came to mind, even a few snake/rat heads that could be shaped into beaks. At a glance, some of the heads look close in shape to a beak, which is whay had drawn me to designing a blend of rat and chicken skull in the first place.
One of the key things I started considering today was maybe injecting a little snake, I needed to creepify this little guy so I looked into a lower jaw that opens in two parts like a snake's. If I'm going for a beak however, I might have to discard the idea there's a stretchable flap of skin over the lip (no. 9 and 4), which does make it look a lot scarier than the other version. With the tongue I looked at lampreys and leeches - jaw-less creatures that instead of two mouths like most animals, have rows and rose of teeth descending into the throat. Both lampreys and leeches sustain themselves by latching onto the flesh of a host and sucking out their blood. Colo Colo's tongue could work like a vacuum cleaner, sucking up saliva and mucus that lines the inside of the mouth, or it uses a mini-tongue while the bulk of the larger tongue acts as a hose for what the mini-tongue collects.
Or maybe a mix of both - scaly back and thighs and a fleshy underside? This sort of thing might be better visualised with colour than line drawings.