n gargantuan animal 

Perception +18; low-light vision, scent (imprecise) 30 feet

Skills Athletics +19, Stealth +19

Str +7 Dex +5 Con +5 Int -4 Wis +4 Cha -2

Deep Breath A platecarpus can hold its breath for 2 hours.

AC  27; Fort +17, Ref +19, Will +14

HP 137

Speed 5 feet, swim 80 feet

Melee [>] jaws +21, Damage 2d12+10 piercing plus Improved Grab

Melee [>] tail +19, Damage 2d6+10 bludgeoning

Aquatic Drag [>] Requirements The platecarpus has a creature grabbed; Effect The platecarpus Swims up to half its Speed, carrying the grabbed creature with it. Strafing Chomp [>] The platecarpus Swims up to its Speed, making one jaws Strike at any point along the way. The Strike deals half damage.

Swallow Whole [>] (attack) Large, 2d6+5 bludgeoning, Rupture 18.

Vicious Strafe [>>] The tylosaurus Swims up to its Speed. It can make one jaws Strike and one tail Strike at any points during its movement, each attacking a different target.

Bestiary 3, page 178.