Scientists on Thursday said fossils of 19 individuals of a dinosaur called Limusaurus, ranging in age from under a year to 10 years, showed that juveniles had small, sharp teeth but adults developed a toothless beak. Only rarely have scientists found fossils of a dinosaur species ranging from babies to adults, a sequence revealing various anatomical changes that unfold as an animal matures. It had short arms and long, slender legs and may have had down-like feathers covering at least part of its body. It's just that those dinosaurs lost their teeth over time. Experts made the discovery after studying the fossilised skeletons of 19 dinosaurs that had died mired in mud in Xinjiang province, China. “It’s amazing to see all the details of a dinosaur tail – the bones, flesh, skin, and feathers – and to imagine how this little fellow got his tail caught in the resin, and then presumably died because he could not wrestle free,” said study co-author Prof Mike Benton from the University of Bristol. The findings make Limusaurus the first known reptile with the characteristic known as ontogenetic edentulism (meaning tooth reduction or loss in development). Such a transformation is rare among animals, although some still alive today, such as the platypus, also lose their teeth as they mature. The research is based on fossils of a small and slender dinosaur known as Limusaurus inextricabilis, part of the theropod group of dinosaurs which were the ancestors of modern birds.
It is discovered that the Limusaurus dinosaur shed its teeth as it matured.