I've been reading on biological classification of the animal kingdom and have come across the New World and Old World terms a few times when they are applied to ranks (family, as much as I could find). Some examples of what I mean:
- Old World porcupine vs. New World porcupine.
- Old World rats and mice vs. New World rats and mice.
- Old World vulture vs. New World vulture.
Old World X and New World X are usually not considered closely related. I assume this is because (at least partially) they evolved separately long enough to be distinct, if they were even related (at a non-trivial level) to begin with.
Is this naming scheme only thanks to convergent evolution? Researchers found families (or species etc.) in the new world that look like families in the old world and called them New World X, which prompted the other to be Old World X? I understand that a good deal of this classification was done in the 19th century when diagnosis tools were limited and conventions varied.