Buddys bearded dragons constantly flick their tongues and that makes them particulary at risk. Small dirt particules if they cant be spited out will be ingested and small rocks can not only make serious inpaction but also shoke a animal. Why do you think that pellets for bearded dragons have such sucess? Because they are quite inquisitive animals and anything new will be inspected even if is quite diferent from a natural food sorce. I can live with the fact that some people use sand because a lot of people aparently use it with no harm effects (even if there are documented cases of impaction in wich sand was involved ,even one that happened to a friend of mine). But small rocks?! I mean I have a image in book that shows a young beardy trying to eat a pebble. Thats is just asking for trouble. Also dont forget that in their natural habitat animals are in a constant battle for survival and there is litle time for thinking about eating the substrate (some especulate that animals that do this kind of thing do it by boredom
) In the wild there´s always something for them to nible on. Its also possible that because beardys have been bred in captivity for so many generations now, some of their old survival skills have been lost
Also dont forget that this thing of beardys being terrestrial just like blue tongue skinks,always living on the ground is a thing of captivity made out of misconseptions. On the wild beardys live on the dry bushy savana of the out back but not directly on the sand for most of the time. They are constantly climbing large rocks, follen tree logs and even on kind of high trees. This means that they are not as well prepared to deal with sand say like torny devils
