Well, I don't think they are cosmetic genes like the ones currently in the game, because those genes are are actually from other extisting animals through the concept of Trangenesis, in which you take a gene from an animal's genome and stick it into another, and what they are really are just color and (occasionally) pattern changers. I also highly doubt they would be true model replacements, because do you think it's a fair permanent change for every single person in the world who plays the game? I don't think so.
I do believe they are some kind of dinosaur cosmetic changes, but if what kind I'm not sure. Nobody truly knows yet, but we all will have to wait and see.