n large animal 

Perception +9; low-light vision, scent (imprecise) 30 feet

Skills Athletics +10, Stealth +11

Str +5 Dex +4 Con +3 Int -4 Wis +2 Cha -2

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

AC  19; Fort +10, Ref +11, Will +7

HP 46

Speed 5 feet, swim 35 feet

Melee [>] jaws +12, Damage 1d12+5 piercing plus Grab

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) Medium, 1d6+2 bludgeoning, Rupture 10.

Bestiary 3, page 178.