Bolas can not be used against a baryonyx but you can trap it somewhere and bring what ever taming equimpment you have that isn't a slingshot.
Baryonyx
The Baryonyx is a large crocodile-like predator. While it might lack in attack power, its ability to swim extremtly fast makes it a fierce opponent — especially with its ability to travel on both land and in water.
Player-written tips for taming, using, and fighting the Baryonyx in ARK: Survival Ascended & Evolved.