What kind of strange animal did I see?

Virgina Opossum - It collapsed because it was playing possum (playing dead). Its a defense mechanism. Opossums are not known disease carriers. You need not try to avoid them. They are harmless. It was just looking for some food. Next time one falls over go pick it up by the tail and take a good look at it;^) Opossums have a very short life span. They most often never live past two or three years of age. And yes it is North America's only marsupial. Goes good with sweet potatoes roasted.