Original: Venom has been known in the families Caenophidia, Anguimorpha, and Iguania and has been shown that it evolved a single time along these lineages before the three families diverged because all lineages share nine common toxins.
Simplified: Venom in the families Caenophidia, Anguimorpha, and Iguania evolved once, then the three families diverged. All three lineages share nine common toxins.