Well, here's a threzinosaurus I did a while ago, converted to 3.5 for your convinience. Threzinosaurs, BTW, turned out to be their own family, of which the previously enigmatic Segnosaurus is now a part of. Deinochierus is believed to be a mammoth ornithomimid.
Therizinosaurus
Huge Animal
Hit Dice: 16d8+128 (200 hp)
Initiative: +5
Speed: 30 ft (6 squares)
AC: 18 (-2 size, +1 Dex, +9 natural)
Attacks: 2 claws +19 melee, bite +16 melee
Damage: Claw 2d8+8 (19-20, x4), bite 1d4+4
Face/Reach: 15ft/10ft
Special Attacks: Augmented criticals, rend 4d8+12
Special Qualities: Low-light vision, scent
Saves: Fort +18, Ref +11, Will +6
Abilities: Str 26, Dex 12, Con 26, Int 2, Wis 12, Cha 10
Skills: Listen +10, Spot +11
Feats: Alertness, Endurance, Improved Critical (claw), Multiattack, Run, Weapon Focus (claw)
Climate/Terrain: Warm forest, hills, plains or marsh
Organization: Solitary, pair, flock (3-6)
Challenge Rating: 10
Treasure: None
Alignment: Always neutral
Advancement: 17-32 HD (Huge), 33-48 HD (Gargantuan)
The therizinosaurus is a bizarre omnivorous dinosaur that, while relatively docile, is dangerous when provoked.
Therizinosaurus stands about 20 feet tall and about 30 feet long. Unlike most dinosaurs, it has a semi-erect posture instead of holding itself parallel to the ground. Its arms are long and apelike, ending in three razor-sharp claws. It has a long neck and a disproportionately small head, with both teeth and a beak. A downy coat covers its entire body.
Therizinosaurus eats mostly fruit, leaves and insects (tearing open termite mounds with its massive claws), but is not averse to scavenging. It will also eat the meat of anything it slays in defense.
Combat
Therizinosaurus, when riled, attacks with its massive claws, tearing at its opponents flesh until it dies. The kills of a therizinosaurus tend to be messy, a fact which makes them avoided by all intelligent inhabitants of their territory.
Augmented Critical (Ex): The claws of a therizinosaurus are very thin and razor sharp. On a successful critical hit, the claw attacks deal quadruple damage.
Rend (Ex): If a therizinosaurus hits with both claw attacks, it latches on and tears its opponent’s flesh. This attack automatically deals an additional 4d8+12 points of damage.
Demiurge out.
