iblically, serpent was a relative term, relative to context. The Genesis context in question is the pre-cursed serpent kind which had not yet been cursed to be close to or down to the ground belly crawlers.
Whatever you believe, this is what is clearly implied in the Genesis record which emphatically implies that the pre-cursed serpents were not belly crawlers.
A Dinosaur isn't a snake with legs.... So your explanation still is absurd.