Due to his experience working in zoos across the country and abroad, Robert Muldoon knew that certain animals were more likely then others to be frequent escapees. In his opinion, Monkeys and Elephants were the most common and well known cage breakers. Mostly due to their dexterity in opening cage doors. However, he also knew that animals such as Moose and Pigs broke free of their cages frequently, being able to manipulate cage doors with their snouts as easily as an elephant could with his trunk.He knew from the start that the Velociraptors had a special talent for escaping. It was due to his ease of escape that he felt that certain dinosaurs were too dangerous to be held in a park setting.