Four-footed and landbound pseudo-avians that are two metre tall when sitting up. Their front-hands bend out of the way when walking. An extra knee/elbow facilitates grasping and feeding. Rear legs have a bony extension, letting them balance on four points when sitting up. The breastplate of a Kwackoo exteds over half a metre from its lower thorax, covering mouth and breathing nostrils.
The head is incredibly streamlined with no surface breaks. The top ridge shelters a hearing organ. On either side are triangular fins, mounted on muscular stalks. These contain optical sensors.
In their original form they hunted in flocks of pterodactyl-like predators, using primitive nets to attack and consume all sorts of land and sea beasts, driving many to the verge of extinction. The Gubru were impressed and got a contract to adopt them. Under most circumstances the Kwackoo show complete loyalty to their masters.