Like a big lizard, a male dingum creeps through the grasses of the hot, central Australian plains of the Outback, hunting small mammals (australodelphian marsupials, monotremes and few placental mammals), reptiles and insects in the dry tussocks. Suddenly a dark shadow sweeps across as a hunting pterodactyl pterosaur hurtles down from the sky. In an immediate reaction, the dingum arches his back and dips his head. A fin of skin supported by struts of bone springs up from his curved back and presents a gaudily-colored sail to the attacker, a sudden burst of garish color against the drab grasses. The crest on the back of the head pops up a frill of spines, each one poisonous enough to kill a large attacker. The pterosaur breaks off its attack, instinctively knowing that these colors mean dan