n gargantuan animal 

Perception +15; low-light vision, scent (imprecise) 30 feet

Skills Acrobatics +14, Athletics +19

Str +7 Dex +2 Con +5 Int -4 Wis +1 Cha +2

AC  26; Fort +19, Ref +16, Will +13

HP 150

Speed 30 feet, climb 30 feet

Melee [>] fist +21 (agile, reach 20 feet), Damage 2d8+10 bludgeoning

Melee [>] jaws +21 (reach 10 feet), Damage 2d10+10 piercing

Mangling Rend [>>] A megaprimatus makes two fist Strikes against the same target. If both hit, the attack deals an additional 2d6 bludgeoning damage, the target is flat-footed, and the target takes a –20-foot status penalty to all Speeds until the end of its next turn.

Terrifying Display [>>] (auditory, emotion, fear, mental) The megaprimatus beats its chest in a terrifying display. Creatures within 50 feet must attempt a DC 27 Will save. While a creature is frightened by this ability, it is flat-footed to the megaprimatus and to gorillas. Critical Success No effect and temporarily immune for 1 minute.Success The creature is unaffected.Failure The creature is frightened 1.Critical Failure The creature is frightened 2 and fleeing until the end of its next turn.

Bestiary, page 23.