Dinosaur, Stegosaurus
This huge dinosaur has a small head, twin rows of sharp dorsal plates, and a muscular tail terminating in a set of bony spikes.

Stegosaurus (CR 7; XP 3,200)
N Huge animal
Init +6; Senses low-light vision, scent; Perception +16
Defense
AC 22, touch 10, flat-footed 20
(+2 Dex, +12 natural, –2 size)
hp 90 (12d8+36)
Fort +13, Ref +10, Will +5
Offense
Speed 30 ft.
Melee tail +16 (4d6+12 plus trip)
Space 15 ft.; Reach 15 ft.
Statistics
Str 27, Dex 14, Con 17, Int 2, Wis 13, Cha 10
Base Atk +9; CMB +19; CMD 31 (35 vs. trip)
Feats Cleave, Great Fortitude, Improved Initiative, Improved Overrun, Power Attack, Weapon Focus (tail)
Skills Perception +16
Ecology
Environment plains
Organization solitary, pair, or herd (3–12)
Treasure none

The stegosaurus is one of the most distinctive-looking dinosaurs—its twin rows of dorsal plates and spiked tail are enough to give most predators second thoughts before attacking. It is 30 feet long, 14 feet tall, and weighs 5,000 pounds.

Stegosaurus Companions
Starting Stats: Size Med.; Speed 30 ft.; AC +6 natural armor; Attack tail (2d6); Ability Scores Str 10, Dex 18, Con 10, Int 2, Wis 12, Cha 10; Special Qualities low-light vision, scent.

7th-Level Adv: Size Large; AC +3 natural armor; Attack tail (2d8 plus trip); Ability Scores Str +8, Dex –2, Con +4.