Detailed aver at my blog: http://mythadvocate.blogspot.com/2011/04/atomic-dawn-dinosaurs.html
Below is a tidbit
Gwangi (Allotyrannus*)
"He who takes from Gwangi the evil one is cursed." -Tia Zorina, Wise Woman
No. Enc.: 0 (1)
Alignment: Neutral
Movement: 120ft (40ft)
Armor Class: 3
Hit Dice: 15
Attacks: 1 (bite)
Damage: 4d6
Save: L7
Morale: 11
Hoard Class: VII x3
The Gwangi (Gwaan-Gee) is a ferocious and adaptable predatory reptile that averages 15ft tall and 25ft long from nose to tail. These reptiles have a hide much like that of a chameleon, allowing it to change color to blend in with its surroundings. Gwangi are fast and cunning foes, hunting anything that moves. Ranchers in particular are concerned about these beasts, as herds of rabboxen, cattle and horses are extremely tempting to Gwangi, who prefer the relatively easy prey of domestic stock.
Gwangi are generally solitary creatures gathering only for mating, after which the female will be left to tend to the eggs and resulting young. Female gwangi make surprisingly good parents, burying the eggs in rotting vegetation and tending to the young dinosaurs until they reach young adulthood. Male gwangi are cannibals however, and will eat even their own young if an opportunity presents itself.
Mutations: Chameleon Epidermis, Increased CON, Regenerative Capability.
*A species particular to Agartha.