n huge animal dinosaur 

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

Skills Athletics +20

Str +7 Dex +2 Con +4 Int -4 Wis +2 Cha +0

AC  23; Fort +17, Ref +13, Will +13

HP 125

Dorsal Deflection [R] Trigger The stegosaurus is targeted with a melee attack. Effect The stegosaurus leans its dorsal plates into the attack, gaining a +2 circumstance bonus to its AC against the triggering attack. If the attack misses, the stegosaurus Steps after the attack.

Speed 25 feet

Melee [>] tail +18 (sweep, reach 15 feet), Damage 2d8+9 piercing

Melee [>] foot +18 (reach 10 feet), Damage 2d6+9 bludgeoning

Trample [>>>] Large or smaller, foot, DC 25

Bestiary, page 98.