Using a Spell of Dehydration or a Wand of Pickling, some monsters can be transformed into a dried, miniature state. Though completely inert, the monsters can be reanimated by immersing it in water. Though the reason for it is unclear, Dinosaurs from the Thunder Plains and the common Terrible Lizard are notably susceptible to this and after dehydration, will remain viable for many years.
Some clever mages will carry a bag of such creatures and reactivate them whenever the need for a rampaging dinosaur is required.
However, it should be noted that to fully revive the small strip of slightly spongy leather into a three ton rampaging monster, the water required is equal to the amount initially lost.