Actually, the kangaroo was not 'discovered' by Cook. It was already well known by the local residents at the time of Cook's arrival in 1770. The story goes that Cook pointed at one of the strange beasts and asked an Aborigine, "What do you call that?" The man replied: "Kangaroo." It was later learnt that in the local dialect, "kangaroo" means "What you talkin' about, white man?". Or something like that.