A new robust enantiornithine bird from the Lower Cretaceous of China with scansorial adaptations

ABSTRACT

We describe a new enantiornithine bird, Fortunguavis xiaotaizicus, gen. et sp. nov, from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation in northeastern China. The new taxon has a strongly dorsoventrally bowed furcula indicating that enantiornithines evolved furcular morphologies in parallel with ornithuromorphs. The new specimen has very robust limbs compared with other enantiornithines and has an unique foot morphology with metatarsal II much shorter than metatarsal IV, robust pedal digits, and strongly recurved pedal unguals. Although recurved unguals characterize Enantiornithes, the extreme curvature present in Fortunguavis suggests scansorial specialization in this species. These features hint at a unique ecology for this taxon and further increase the known diversity of body plans in Early Cretaceous enantiornithines.

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ACKNOWLEDGMENTS

We thank C. Sullivan for commenting on the manuscript and T. Stidham for discussion. We also thank Y.-T. Li for preparing the specimen and J. Zhang for photography. We are grateful to A. Dececchi and H. Larsson for providing the data for the statistical analysis. We thank the reviewers D. Marjanović and L. Chiappe and the editor T. Worthy for their constructive comments and suggestions to improve the manuscript. This research was supported by the National Basic Research Program of China (973 Program, 2012CB821906), the National Natural Science Foundation of China (41172020), and the Chinese Academy of Sciences.

Handling editor: Trevor Worthy