Machinery more complicated than clockwork is forbidden in Dinotopia. Furthermore, anyone in position of a sunstone is considered a criminal and to be put to death upon sight.
Even clockwork is considered too dangerous for popular consumption, and only allowed for official purposes.
While guns and their mechanisms are known in Dinotopia, carrying one is tantamount to carrying a sunstone. Nevertheless, there is a black market that deals in such things and the concealment thereof. Like all weapons in Dinotopia, guns tend to be on the small side for unobtrusiveness.