Researchers performed an extensive analysis of 19 fossils of ceratosaurian theropod dinosaurs also known as Limusaurus inextricabilis. They discovered that the extinct reptiles had teeth only as babies, which they gradually lost as they grew up. This is the first type of dinosaur with such a characteristic ever discovered.
Shuo Wang, a researcher at the Capital Normal University in Beijing, and the leader of the study, which was published in the journal Current Biology, revealed that the toothed jaws in juvenile ceratosaurian dinosaurs gradually transition to being toothless as they mature into full-grown dinosaurs.
This discovery coupled with other evidence led scientists to conclude that the baby dinosaurs were very likely omnivorous but as they grow up, they gradually transition to a plant-based diet, for which normal canine teeth are not very useful.
The discovery of the first baby Limusaurus fossil took place in 2001, which was found in the Upper Jurassic Shishugou Formation located in the northwest of China. In the following years, Wang and his colleagues found additional fossils, which at the beginning it wasn’t entirely clear if they belong to the same dinosaur species. Researchers were confused by the fact that although the fossils bear striking similarities, one had teeth while another was toothless. As such, scientists thought they discovered two different types of ceratosaurian dinosaurs.
They were able to discover that the fossils belong to the same species of dinosaurs only after they performed the phylogenetic analysis. Scientists were surprised to discover that the fossils the same characteristics, except for the teeth. This discovery led them to conclude that the fossils of up to 19 specimens they found, represented the same species, but in a different stage of their growth, from baby to adult.
Although this marks the first discovery of a dinosaur which loses its teeth as it matures, the phenomenon isn’t that rare in current animals. For example, a number of fish species lose their teeth as they grow, as well as platypuses. No current or previous reptiles were found to have this trait.
What do you think about this discovery? Should scientists reexamine their previously discovered fossils for this type of characteristic?
Image credit: Geoge Washington University