The 3-meter (10 feet )-long gwanna lives in family groups of four or five adults and a number of young. The sparse grasses could not support larger herds. The gwannas' sandy color camouflages them from a distance. They move mostly by walking or running, but when faced with sudden danger, such as finding a poisonous dingum in the grass, they leap out of the way, flashing their flank patterns as a warning to others.
The gwanna has evolved mouth parts that can deal with tough grasses. A solid horny beak at the front of the mouth crops the grass. It is then pulled by the tongue to the cheek-pouches where it is chewed thoroughly by a series of constantly replaced grinding teeth. The brightly colored head crest is used for signaling during the mating season.
The hand can be used for walking (two hooves), for grasping (two fingers) and for fighting (thumb spike).
The Gwanna, Gryllusaurus flavus, is a kangaroo-like rhabdodontid, descended from Muttaburrasaurus, that inhabits the deserts and desert scrubs of the Outback, in The New Dinosaurs: An Alternative Evolution.
The Outback interior of the Australian continent is very dry. Almost two-thirds of its area is desert or dry grassland. It is a harsh environment for living things, but not an impossible one. Many animals exist here but the only large one is the gwanna. It is the last survivor of the rhabdodontids, as well as the last of the non-hadrosauroid iguanodonts. These dinosaurs (iguanodonts in general dating back to the Middle Jurassic) are closely related to the basal ornithopods, of which are now found almost all over the world, but the non-hadrosauroid iguanodonts tended to be much larger and had more cheek teeth. On all the other continents of the world the non-hadrosauroid iguanodonts were eventually replaced by the more versatile hadrosaurs, but in Australia they survived in isolation as the hadrosaurs never reached that landmass. The larger number of cheek teeth meant that the non-hadrosauroid iguanodonts were in a better position than the basal ornithopods to evolve into grass-eaters when grassy plains spread in the Miocene. The grasses of the region are not particularly nutritious and a large animal has to range further to find enough to eat. The gwanna lives in small family groups which can move quickly from one area to another seeking fresh pastures. The physical build of the original non-hadrosauroid iguanodont was quite suitable for this way of life and it has not changed dramatically. At rest, the gwanna is on all fours, with its head near the ground. When moving, it is a bipedal animal. Its longer hind legs can bear its full weight, and its body is balanced by the heavy tail as it walks or runs across the open landscape.