A Juvenile Specimen Of Sauropodomorpha From The Lower Jurassic Of China And A Brief Review Of The Lufeng Sauropodomorph Fauna

An incomplete dinosaur skeleton, including a partial skull, recently discovered from the Lower Jurassic Lufeng Formation of Yunnan, China, is here reported. Apart from its small size, little anatomical evidence supports, a priori, the non-adult status of this new sauropodomorph specimen but osteohistological analyses suggest that it is a fast-growing juvenile. This specimen represents only the second occurrence of a juvenile non-sauropodan sauropodomorph in the Lufeng Basin. The anatomy of the new specimen does not match that of other Lower Jurassic immature specimens; although cranial material is preserved, it does not display the diagnostic characters of early sauropodomorphs from the same horizon, namely Lufengosaurus, Yizhousaurus and Yunnanosaurus. Our phylogenetic analysis places the new specimen in a position relatively distant from other Chinese sauropodomorphs, and corroborates the anatomical evidence showing it is not referable to any known species already excavated in Yunnan. This result is interpreted with caution considering that ontogeny affects phylogenetic reconstruction. A thorough comparison with adult forms, taking into account ontogeny-related characters, suggests that this Lufeng juvenile might represent a previously unknown species of early sauropodomorph.