Mammal-specific scorpion neurotoxins

[Ken Kinman]

Kevin,
     Good point!  In fact, some scorpion (or other) neurotoxins could have perhaps evolved against the ancestors of mammals (mammal-like reptiles) well before the mammals even existed (perhaps against Permian therapsids or even Carboniferous pelycosaurs).  However, it would be extremely difficult to prove, unless we discovered these neurotoxins are actually toxic to some living reptiles (but then they would be amniote-specific).
  ---Cheers,
          Ken