Dino Suggestion: Titanaboa
Titanoboa is an extinct genus of very large snakes that lived in what is now La Guajira in northeastern Colombia. They could grow up to 12.8 m (42 ft) long and reach a weight of 1,135 kg (2,500 lb).
If added, the Titanoboa would be an 'amphibious snake' more comfortable in water than on land. Acting as an ambush predator, the snake would hunt at the edges of water. Quickly lunging out in bone crushing strikes that would tire the snake but leave the prey de-buffed and slow moving due to the bone damage, allowing the snake to follow and secure its meal once it has enough stamina to do so.
While having high speed and stamina in water, the Titanaboa would have slow movement speed and low stamina on land, permitting only short bursts of speed via its "Sprint". This makes it so while powerful, if the Titanaboa misses an ambush it will not have the backup stamina to pursue a target.
If caught in the open it would have a "Coil" ability to make its length defendable.