The animal, named Chakisaurus nekul, was found in the Pueblo Blanco Natural Reserve, an area rich in fossils where many mammals, turtles, and fish have been found along with other species of dinosaur
The 26-year-old was one of around 150 people who took part in a two-day live action battle between orcs, elves, knights and other fantasy characters from the online role-playing game that has become a cultural phenomenon since launching in 2004.
Ruzicka designed and made his own fur lined flowing gowns, decorated with skulls.
To complete his costume, he painted his face blue and dyed his beard a glowing orange before taking his place in the forest as the Azeroth fighters defended their planet against the Burning Legion.
"I always forget the real world, it relaxes my mind,” he told Reuters.
The event, which concluded on Sunday at Kamyk nad Vltavou, 70km (40 miles) south of Prague, has been going for 16 years.