Approximately what percent of the
American sawfish's overall length
is made up of its rostral saw ?

The toothy snout is usually between 1/4 and 1/5 of the sawfish's total length. The sharp awl-like teeth are not true teeth at all; they are really modified scales, which enlarged over time and became embedded deep inside the rostrum.
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Correct. In the American sawfish
specificaly it can be as much as
30% of its overall length !

Thanks for the answer J.R. !