Limusaurus

Type Species: Limusaurus inextricabilis

Classification: Dinosauria – Saurischia – Theropoda – Ceratosauria – Neoceratosauria – Abelisauroidea – Noasauridae – Elaphrosaurinae 

Time Period: Late Jurassic

Location: China

Diet: Omnivorous to Herbivorous   

The theropod Limusaurus was a slender animal about six feet long in adulthood. It had a long neck and legs and very small three-fingered hands. Its name literally means “impossible to extricate from mud,” in reference to the Shishugou Formation mud pits in which these specimens died. Limusaurus is fascinating in that this dinosaur underwent a dramatic morphological transformation as it aged: while juveniles were toothed, these teeth were completely lost and replaced by a beak as they reached adulthood! The change to toothlessness in adults likely corresponded to a dietary shift from omnivory to herbivory, a theory bolstered by the fact that gastroliths (stomach stones) were found in adults. Since many specimens were found together, it’s possible that Limusaurus lived in groups. These theropods were similar to the Cretaceous ornithomimids as well as the Triassic non-dinosaurian shuvosaurids; thus at least three times within the archosaur lineage, these herbivorous adaptations evolved separately in instances of convergent evolution (in which different organisms, unrelated, evolve similar traits to deal with similar environmental pressures).