(juvenile) monitors - small mammal pests - Mesozoic counterpart?

[B tH <soylentgreenistrex@yahoo.com>]

They can't survive the winters here outside,
but if one were to pick up a pair of say, 
moderate-sized juvenile (non-Komodo) monitors
and turned them loose in the large group of
oaks, pecans, and maples around here in SC,
would they go after an overpopulation of 
pesky, get-in-the-rafters, gnaw-on-the-shed 
rats-with-tails squirrel population with
any success?

There was a cat in the neighborhood that would
go to each nest and singly paw-out the pups,
drop them to the ground, then descend and 
gobble them - but she's no longer around.

Have fossil stomach-contents of monitor-like
lizards ever been found?  Any early, small
skwarl-like mammals in the diet?

Of course, short of the mockingbirds and starlings, I'd hate to see monitors 
devestate
the bird population around here - just want
them to munch on squirrels and mice.