It has been decided a while ago that there will be six main classes of characters (species) for the game, longnecks, threehorns, spike- / clubtails, swimmers, flyers, and fast-runners. To allow for a greater variety of outward appearances of playable characters we hope to have several subspecies (kinds) for each species, each of which would have exactly the same performance values, but different looks. For example in case of the longneck there could be an Apatosaurus, a Diplodocus, and a Brachiosaurus version etc.
We are far from that stage of development now, but there may be more ways to individualize the different characters if for example we could pick from a selection of different "details" such as eyecolors, different types of spinecrests, different color patterns etc
I've drawn some sketches for some types of characters that might appear in the later game. So far I have drawn sketches for four species, always one sketch with some of the different kinds and another pointing out some of the details which might be variable to allow for a greater individuality of the characters.