In Red Dwarf (season one episode one), Lister doesn't know what an iguana is when Rimmer mentions the word:
RIMMER: The bright side? What bright side? I'm dead, I'm composed entirely of light, and I'm alone in space with a man who'd lose a battle of wits with a stuffed iguana. Where's the bright side?
LISTER: What's an iguana? And look, look, you're not dead, are ya? I mean, you're dead! But you're not dead dead, because you're still here, aren't you?
Is there any canon saying that iguanas are extinct in Red Dwarf? Or did Lister just never hear about or see one in his life?