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, 111 (29), 10624-9

Flight Performance of the Largest Volant Bird


Flight Performance of the Largest Volant Bird

Daniel T Ksepka. Proc Natl Acad Sci U S A.


Pelagornithidae is an extinct clade of birds characterized by bizarre tooth-like bony projections of the jaws. Here, the flight capabilities of pelagornithids are explored based on data from a species with the largest reported wingspan among birds. Pelagornis sandersi sp. nov. is represented by a skull and substantial postcranial material. Conservative wingspan estimates (∼6.4 m) exceed theoretical maximums based on extant soaring birds. Modeled flight properties indicate that lift:drag ratios and glide ratios for P. sandersi were near the upper limit observed in extant birds and suggest that pelagornithids were highly efficient gliders, exploiting a long-range soaring ecology.

Keywords: Aves; Oligocene; fossil; paleontology; pseudotooth.

Conflict of interest statement

Conflict of interest statement: Editor P.E.O. served as a committee member for the dissertation of D.T.K. in 2007.


Fig. 1.
Fig. 1.
(Upper) Reconstruction of P. sandersi (elements preserved in the holotype are shown in white) with D. exulans (Royal Albatross; 3-m average wingspan) for scale. (Lower) P. sandersi holotype (ChM PV4768) skull in (a) dorsal, (b) ventral, (c) left lateral (mandible in medial view), and (d) right lateral views (mandible in lateral view). Right humerus in (e) caudal and (f) cranial views. Scapula in (g) lateral and (h) medial views. (i) Partial furcula femur in (j) cranial and (k) caudal views. Tibiotarsus in (l) cranial and (m) caudal views. Fibula in (n) lateral view. Tarsometatarsus in (o) dorsal view (distal portion exposed in the medial view because of deformation) and (p) rotated to show the distal portion in dorsal view. (q) Pedal phalanx. cc, Lateral cnemial crest; fac, fossa aditus canalis neurovascularis; fc, facet; haf, humeral articular facet; ie, intercotylar eminence; j, jugal; lf, lateral furrow; mtII, metatarsal trochlea II; nfh, nasofrontal hinge; pf, pneumatic foramen; pp, paroccipital process; sf, subcondylar fossa; sup, supra-angulare; sw, swelling on crista deltopectoralis; syn, synovial joint; tb, tubercle; trf, transverse furrow.
Fig. 2.
Fig. 2.
(A) Glide polars and (B) lift:drag ratios for P. sandersi modeled in Flight 1.25 (2). Results of 24 analyses using different combinations of mass (21.9–40.1 kg), wingspan (6.06–7.38 m), and aspect ratio (13.0–15.0) estimates in blue; modeled values for a frigatebird (Fregata magnificens; red), albatross (Diomedea chrysostoma; black), and vulture (Coragyps atratus; green) from the Wings database in Flight 1.25 are shown for comparison. Individual analyses are presented in SI Appendix.
Fig. 3.
Fig. 3.
Power curves for P. sandersi calculated in Flight 1.25 using (A) the 21.9-kg mass estimate and (B) the 40.1-kg mass estimate with maximum estimated aerobic power for comparison. A and B each display the results of 12 iterative analyses with alternate combinations of wingspan and aspect ratio estimates. In A, horizontal flight under solely aerobic power is supported by iterations with 6.4-m wingspan and 14.0–15.0 aspect ratio (light blue) as well as all iterations with 7.38-m wingspan (green). All other runs did not support horizontal flight capabilities under solely aerobic power. Individual results for all 24 runs are provided in SI Appendix.

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