The classical idea of venom in reptiles was that several snakes, as well as 2 lizards, were venomous, and it seemed to work fine. Then, Toxicofera as a clade begins to get support, and the hypothesis that Komodo dragons used bucal bacterial flora as a way of killing prey is disproven, pretty much due to the presence of venomous glands and that venom and large wounds are faster killing strategies that saepticemia...

However, that has given me some questions: Is the clade, at least, ancestrally venomous, or at least the venom glands have all a common origin? Would that mean that the concept of "non-venomous" snake would turn to be meaningless (and by extension, bites from legless squamates would always be a bit problematic)? And, could Mosasaurs (which I always forget if their sister clade is monitors and helodermatids or snakes) have venomous bites (that'd be overkill and not very needed, but then again, there ARE sea snakes)?

Thanks for the answers, and sorry for my weird grammatical choices.

Hi Emilio -

The current model is that a core set of venom genes evolved once at the
base of the toxicofera, and the clade is ancestrally venomous. The last
common ancestor for the toxicofera probably had incipient venom glands
in both the mandibular and maxillary regions.  Snakes favored the
development of the maxillary gland and reduced the other, while
anguimorph lizards did the reverse.  However, this does not mean that
there is no such thing as a non-venomous snake.  A number of snakes, for
example the ratsnakes and probably also boas and pythons (constrictors
that don't need venom) have secondarily lost their venom glands.  In
addition, there have been a number of independent venom protein
recruitment events - wherein a pre-existing protein doing something else
gets coopted - and venom protein evolution within the toxicofera, so
not all venoms are equal in potency, or indeed have the same molecular
basis.  Mosasaurs I do not know much about, maybe someone else on the
forum with more of a grounding in fossils can fill this in.  To take a
stab at it, I would say that given that mosasaurs group with the monitor
lizards, which have been placed squarely in the toxicofera in recent
molecular phylogenies, its likely they did have venom.