Corresponding Animal Classes to Continents

Need some help, I'm having trouble corresponding animal classes to continents. If I told you the reason for this, I'm certain there would be bias. I also don't want my bias to influence it though I'll probably somehow come off as a bigot even with your answers.

Anyways, here are the classes and continents I chose:

Africa, Asia, Europe, North America, Oceania, South America Arthropod, Bird, Fish, Mammal, Mollusk, Reptile

A continent can only have one class correspond to it and a class can't be corespondent to multiple continents.

Do you have any criteria for the allocation? Based purely on my own subjective mental association, it'd probably be:

• Africa: Mammals (wide diversity of terrestrial megafauna and great apes)
• Asia: Reptiles (saltwater crocodile, reticulated python, king cobra, Komodo dragon)
• Europe: Fish (beluga sturgeon, wels catfish, pike, trout, salmon)
• North America: Birds (bald eagle, turkey, Canada goose, puffin - plus the Audubon Society)
• Oceania: Mollusks (giant Pacific octopus, blue-ringed octopus, colossal squid)
• South America: Arthropods (bullet ant, army ant, Amazon giant centipede, tarantula)

It sounds like a very arbitrary set of classes and rules. In Real Life, Europe has immense diversity of most/all of those classes; for Oceania, Australia is crawling with marsupials, reptiles and birds and New Zealand has an immense variety of birds, a number of reptiles but few native mammals.