Camarasaurus
Colossal Animal
Hit Dice: 18d8+129 (210 hp)
Initiative: -1
Speed: 30ft (6 squares)
Armor Class: 10 (-8 size, -1 Dex, +9 natural), touch 1, flat-footed 10
Base Attack/Grapple: +13/+39
Attack: Tail slam +15 melee (3d6+15)
Full Attack: Tail slam +15 melee (3d6+15)
Space/Reach: 40ft/30ft
Special Attacks: Trample 6d6+15
Special Qualities: Low-light vision, scent
Saves: Fort +20, Ref +10, Will +10
Abilities: Str 30, Dex 9, Con 24, Int 1, Wis 14, Cha 7
Skills: Listen +14, Spot +15
Feats: Alertness, Diehard, Endurance, Great Fortitude, Iron Will, Toughness
Environment: Warm forests, hills and plains
Organization: Solitary, pair or pod (6-36)
Challenge Rating: 9
Treasure: None
Alignment: Always neutral
Advancement: 19-54 HD (Colossal)
Level Adjustment: -
This massive quadruped has a short box-like head atop a long neck, a stout but powerful tail and an elephantine hide.
The camarasaurs are one of the smaller and weaker types of sauropod.
Camarasaurs, while large (around 60 feet long and 20 tons), are dwarfed by most other sauropods, and they are small enough to be targeted by allosaur packs and other carnivorous dinosaurs. As such, they live and travel in large herds for protection. Their nearly horizontal backs and short necks allow them to browse short trees and saplings.
Combat
When attacked, camarasaurs are capable of using their powerful tails in defense, but are just as likely to run away.
Trample (Ex): A camarasaurus can literally run over any creatures in its way that are of Gargantuan or smaller size. Creatures trampled must make a Reflex save (DC 29 half) or take 6d6+15 damage. The save DC is Strength based.
The Wikipedia article makes me think we should replace the tail slap with clawing slams, like Brachiosaurus.