Chiappeavis magnapremaxillo was named by O'Connor et al. (2016) [A large pengornithid enantiornithine with the following unique features: ventral margin of the premaxillary corpus convex so that the imperforate region of the premaxilla is proportionately larger; nasal processes of premaxilla nearly reach frontals; eight fused sacral vertebrae; lateral margins of median trabeculae concave and xiphial region demarcating a narrow angle; proximal articular surface of the tibia laterodistally inclined.]. It is not extant. Its type specimen is STM29-11, a skeleton (a nearly complete and fully articulated subadult individual preserved in a single slab, preserving impressions of the remiges and rectrices). Its type locality is Lamadong, Jianchang, which is in an Aptian lacustrine sandstone/mudstone in the Jiufotang Formation of China.