[Vivisectus]

I think we should systematize based on their distinctive features, and then we can see if we cannot create a classification system. Obviously this will have to be done the old-fashioned way, as we cannot use genetics to differentiate the different species.

I propose that we call the infectious type of Zombie that involves dead humans coming back to life as Zombi Romeronis, since Romero developed the archetype of this type of zombie. These zombies

1: Start as infected living people who die and are then transformed into zombies
2: Have highly infectious bites that carry a lethal disease that kills, generally within 48 hours
3: Can be damaged, but not killed unless the brain is destroyed
4: Are generally slow and shambling

Zombi Romeronis Romeronis, is the archetype of this kind of zombie. They seem to retain some vague, "instinctual" memories of their previous lives. They walk about in a shambling, uncoordinated way and utter bestial grunts and groans much of the time. They are one of the slower types of zombies: I do not think I have seen them sprint or jump.

Romeronis Romeronis is in many cases a much more intelligent zombie than your average shambling undead, sometimes even capable of almost human emotions, and capable of learning or of using experience from their non-undead existence to get to food.

In later movies, rare zombies display behavior that could arguably justify giving them a further classification: "Zombi Romeronis Romeronis Sapiens", who seem to display more-than-rudimentary problem solving skills, can learn from observation quite quickly, and even seem to care about what happens to other zombies and to influence the actions of other zombies.

Zombi Romeronis Perambulatus such as seen in "The walking dead" is another subtype of these. Much more like automata and seemingly devoid of anything but the most rudimentary intelligence, this zombie staggers about slowly most of the time, but is occasionally capable of a short burst of speed, a lunge, or a pounce.

The disease that causes this kind of zombie-ism has 2 types: the acute deadly form that kills, and a latent form that can be carried without clear symptoms, but which will cause the carrier to become a zombie after death. Or possibly these are actually 2 distinct afflictions?

There are also 2 distinct behavior patterns: mobile opportunistic hunting, or static ambush hunting.

The mobile type reacts strongly to noises, seems to have fairly poor eyesight, and rather bad coordination and speed, although hey are capable of brief burst of a jogging run when excited and close to food.

However, sometimes we have seen inactive lurking zombies in situations where there is plenty of sound and activity: in the episode where the veterinary loses his leg they run over what seems to be a corpse after a noisy fight.

It can be that some choose to be ambush predators rather than actively roaming opportunistic hunters, or that we are dealing with 2 different types.