Info dumping here for later organization
Idea for things like Werewolves and other creatures akin to them: Make it a disease caught by bites from feral creatures. It alters the magic of an anthro (and in some cases a feral) that alters their appearance depending on the creature. For example, some wolves bitten by a feral with this disease will find their fur growing out faster/longer, their senses sharper, and their energy higher. Deer, however, will find themselves with sharper teeth, hooves that grow faster, and a shift in the angle their horns grow at (mostly with sharper ends and points that turn entirely to the front of the horn). Even magical creatures aren't immune to this, with dragons often finding their spines sharper, their teeth longer, and the edge of their wings harder. An increase in the production of an undercoat/down feathers is common in species with them, as well as sharp teeth and an energy spike. There are remedies, but nothing that permanently destroys the disease itself. It may bring the appearance of the afflicted back to how they looked before they were infected, but one missed dose is all it takes to give them their extra fluff. How this disease affects an anthro varies between each individual. Some find it necessary to take a remedy due to how severe the change is, such as a massive increase in fur density in a coyote living in the Thundering Barrens. Others may never know they were infected at all, simply never noticing their fangs are just a bit sharper than before. Anthros cannot pass this to other anthros, but ferals can pass it to each other. It's called Full Moon Mania, only because the first case of this was spotted in a feral wolf pack on a full moon. This led those researching the phenomenon to falsely believe the full moon caused the change in the first place. The misconception of mindlessness and increased signs of anger or rage comes from this observation as well, seeing as the infected attacked the feral wolf pack, transforming them with the disease. In reality, this outsider was being driven out of the pack in the first place, hence the observed aggression.
Idea for anthropomorphizing things like birds and snakes. These creatures have a unique issue to making them bipedal. One is the fact birds are already bipedal, and will need some sort of other attribute aside from speech to separate them from their feral counterparts. One idea is to give them wing claws, like on some feathered raptors. That way they can pick things up with their wing-arms without using their feet (already a bit questionable with dirt roads and the such). May need to be addressed further. As for snakes, the issue comes with the fact they have no limbs at all. Two ideas have been brought up to try and fix this. One is to give them arms and legs, just with longer tails (and possibly longer necks). The problem with this is the fact that they'd become a little too close to dragons and other reptiles, taking away one of the most notable aspects of being a snake: the distinct lack of limbs. The other is to give them the centaur treatment; The torso and up is almost humanoid, perhaps with longer necks, while everything below is serpentine with a thick enough tail to support the upper body. The downside of this is that they wouldn't have legs, which may not fit the anthropomorphic definition of this specific world. May need to be addressed further.
Idea for some fictional creatures: They do exist in this world. Settled on Zaphiara, perhaps separate to the dragons and dinosaurs in some ways depending on the creature. For example, unicorns were first found on Zaphiara, and are often very powerful when it comes to using their magic. Other fictional/mythical creatures need to be discussed, but an idea for a non-Zaphiara animal could be a griffon. Perhaps these hybrids of bird and large feline come in many varieties, and are found throughout Peluna. For example, a snow leopard-snowy owl griffon may have originated from The Sparkling Fields, while a cheetah-roadrunner griffon could trace their origins to The Thundering Barrens. Will need to be further explored for other creatures and how they work.