Flight Performance of the Early Cretaceous Bird Confuciusornis sanctus: Evidence from an Exceptionally Preserved Fossil

The Chinese early Cretaceous Confuciusornis sanctus is the most abundant Mesozoic bird and a model species for studies of early avian evolution. While previous investigations were largely focused on aspects of the anatomy, taxonomy and systematics, and life history and ecology of this bird, there has been minimal research on its flight properties. Our study centers on a well-preserved specimen with exquisite details of its plumage. NHMW 1997z0112/0001 affords novel information on aspects of its skeletal morphology, particularly from the axial and appendicular skeletons, and its plumage provides the opportunity to quantify key flight-related variables including, wingtip, wing chord, body mass, wingspan, and wing area. We use these parameters to provide a quantitative assessment of the flight properties of C. sanctus . Most previous studies have suggested that this species was unable to achieve prolonged flights. However, our results indicate that the capacity for this bird to perform prolonged flights cannot be discarded, given that our data shows it might have been able to combine periods of flapping with periods of efficient low-speed gliding. Specifically, our results indicate that while having slightly less capacity than modern gliding birds, the gliding capacity of C. sanctus would have been significantly higher than that of modern short-term fliers such as land fowl. On the basis of these inferences, we conclude that C. sanctus could fly efficiently for prolonged periods of time when used a combination of flapping and gliding periods.