All the animals with the grey square are Russian Brown Bear, not availalbe here therfore we cannot answer this one unless you mean the syrian brown bear in which case make sure you have the one that is not marked for ES.
Spirit Bear, needs ES/AA to work
Bobcat, all the frogs available for download,
Yacare Caiman, Black-tailed Deer, White-tailed Deer, Dik-dik, Fisher, Clouded Leopard, Nightmare, Phoenix, Miniature Pony, Phorusrhacos, Racoon,
European Wild Cat, Caracal, Himalayan Monal, Fallow Deer,
European Unicorn. again these where all made after ES/AA came out and will not work
All the animals that are invisible [some don't contain the grey square, most do] are fantasy wolf, dingo, arctic fox, red dragon, serval, eastern bluetongued skink, redfooted tortoise, ornate box turtle, eastern timber wolf, southern hairy-nosed wombat.
again all need expansion packs to work
Most of the new downlaods on the database need expansion packs to work. Many creators now have the expansin packs and therfore use the files from the expansion packs to make thier animals etc so even if that animal was based on an animal in the original zt2 its files are more than likely to be taken from an EP and therefore will not work. Tomcat is one of the creators who has animals that you can use for zt2 (look for his files that NOT NOT have either ES or AA after them) and a few of penguinmans files his earlier ones are zt2 stand alones.