Supporting information for:
Flight Performance of the Largest Volant Bird
Daniel T. Ksepka
National Evolutionary Synthesis Center, 2024 W. Main Street, Durham, NC 27705 USA.
Department of Marine, Earth and Atmospheric Sciences, North Carolina State University,
Raleigh, NC 27695 USA.
Contents:
Supporting text: Additional details of geological context and species diagnosis.
Figure S1. Additional fossil birds represented in the Chandler Bridge avifauna.
Table S1. Alternate estimates of primary feather length in P. sandersi.
Table S2. Estimated Gliding Flight Parameters for P. sandersi.
Figure S2. Individual results of analyses 1-12 in Flight 1.25 showing glide polars.
Figure S3. Individual results of analyses 13-24 in Flight 1.25 showing glide polars
Figure S4. Individual results of analyses 1-12 in Flight 1.25 showing lift:drag versus speed.
Figure S5. Individual results of analyses 13-24 in Flight 1.25 showing lift:drag versus speed.
Table S3. Estimated Power Parameters for P. sandersi.
Figure S6. Individual results of power curve analyses 1-12 in Flight 1.25.
Figure S7. Individual results of power curve analyses 13-24 in Flight 1.25.
Supporting References. Locality Data
ChM PV4768 was collected during construction at the Charleston Airport, at a central channel approximately 1.2km from Dorchester Road (SC route 642) by Albert
Sanders and colleagues. All elements were collected in tight association from a single block excavated from Bed 2 of the Chandler Bridge Formation. The Chandler Bridge
Formation is a thin (up to 5m) unit composed of fine-grained, quartz-phosphate sand with silty, calcareous clays occurring locally near the base of the unit (1). Although original efforts to obtain microfossils were unfruitful due to leaching of this permeable unit (2), calcareous nannofossils referable to NP25 have subsequently been discovered (3). These provide the basis for an age of ~25-27Ma (4), in close agreement with an estimate of 27-
28Ma based on the cetacean fauna (5), and placing the unit in the lower Chattian (Late
Oligocene). The Chandler Bridge Formation can be subdivided into three units: Bed 1,
Bed 2, and Bed 3 (1). Bed 2, which yielded ChM PV4768, has also yielded numerous whales and marine turtles (5-6). Bed 2 appears to have been deposited in an open shelf or open bay environment below the wave base (6-7).
Several additional pelagornithid elements have been recovered from Bed 2 of the
Chandler Bridge Formation including a coracoid and two partial humeri (Fig. S1). These elements are substantially smaller than those of the holotype individual of P. sandersi.
Because of poor preservation, it is not possible to determine whether they represent an immature individual of the same species, or an adult of a smaller pelagornithid taxon.
Seven other avian species are represented in the Chandler Bridge Formation, all of which belong to marine groups (Fig. S1). Four species of Sulidae and three species of
Procellariiformes are represented, and will be fully described elsewhere. A total of 28 elements can be assigned to Sulidae (boobies and gannets) based on features including presence of multiple pneumatic foramina on the processus acrocoracoideus of the coracoid, (also present in the otherwise dissimilar Fregatidae and Pelecanidae), a mediolaterally narrow facies articularis sternalis of the coracoid, an extremely deep fossa olecrani of the humerus, and presence of a pneumatic foramen near the dorsal border of the impressio m. brachialis of the ulna (also present in Fregatidae and Pelecanidae) (see
8). Six specimens can be assigned to the small albatross taxon Plotornis (9) based on the combination of a shallow, poorly defined fossa m. brachialis, moderately projected processus supracondylaris dorsalis (in contrast to the elongate processus in extant
Diomedeidae), and elongate tuberculum supracondylare ventrale which extends proximally beyond the level of the processus supracondylaris dorsalis. Finally, two humeri represent Procellariidae (petrels) based on the absence of a pneumatic foramen in the fossa tricipitalis, deep, pit-shaped fossa m. brachialis, and well-developed processus supracondylaris dorsalis.
Figure S1: Additional avian remains from the Chandler Bridge Formation. Pelagornis sp.: (a) right humerus (ChM uncataloged) and (b) left coracoid (ChM uncataloged). Sulidae: (c) left coracoid (ChM PV2851), (d) distal end of right humerus (ChM PV2846), and (e) right tarsometatarsus (ChM PV4737). Plotornis sp.: (f) distal end of right humerus (ChM PV4740).
Procellariidae: (g) right humerus (ChM PV 3407). Abbreviations: fmb - fossa m. brachialis, fo
- fossa olecrani, pf - pneumatic foramina, psd - processus supracondylaris dorsalis.
Additional Comparisons to other species of Pelagornithidae
Comparisons follow recent taxonomy proposals (10-11) to synonymize
Palaeochenoides, Pseudodontornis, Tympanonesiotes, and Osteodontornis with
Pelagornis. The suggestion that Odontopteryx and Macrodontopteryx be synonymized with Dasornis (12) is also adopted. Comparisons below are intended to support the diagnosis of a new species. A full osteological description will be published elsewhere.
Three species of Pelagornithidae were identified from South Carolina prior to the discovery of P. sandersi. Unfortunately, the stratigraphic horizon remains uncertain for all of these specimens. They were originally assigned to the Late Miocene Hawthorne
Formation, but this unit is not exposed in South Carolina. It was previously determined that the fossils are more likely from Oligocene deposits of either the Cooper Formation or
Chandler Bridge Formation (13). The Cooper Formation has since been elevated in status to the Cooper Group and it is evident that the specific unit referred in past work (13) is the Ashley Formation (formerly the Ashley Member). Where both units are in contact, a burrowed unconformity separates the Chandler Bridge Formation from the underlying
Ashley Formation (3). The Ashley Formation has yielded microfossils referable to nannoplankton zones NP24 and NP25 (3) and so is close in age to the Rupelian/Chattian boundary. Pelagornithid fossils collected from the Ashley Formation are thus most likely
~2Ma older than those from the Chandler Bridge Formation (5).
Pelagornis (=Palaeochenoides) mioceanus was named based on the distal end of a femur (14), which limits comparisons. P. sandersi differs from P. mioceanus in having a shallow sulcus on the trochlea fibularis, which is considered a derived feature within
Pelagornithidae (10). P. mioceanus instead exhibits a deep, well-defined sulcus. Based on the overall proportions of the femur, P. sandersi was also approximately 15% larger than
P. mioceanus.
Hopson (15) assigned a fragment of a mandible including several pseudoteeth to
Pelagornis (=Pseudodontornis) longirostris. The holotype of this species is a partial skull of unknown age and locality (16) that appears to have been destroyed in World War II
(13). Comparisons to P. longirostris must rely on figures and descriptions of the holotype, which indicate the caudal portion of the mandible was substantially deeper than in P. sandersi. Although the presence of only one small pseudo-tooth between the largest pseudo-teeth was considered characteristic for P. longirostris (10) the smallest teeth were likely lost due to wear, and thus this pattern may not to be useful for diagnosis (15,17).
While the shape of the mandible differentiates P. sandersi from P. longirostris, the fragmentary nature of Hopson's South Carolina specimen does not permit a confident species referral and it should be considered Pelagornithidae indet.
Pelagornis (=Tympanonesiotes) wetmorei was named based on a fragmentary tarsometatarsus (15). Its exact age is even less certain than the other two specimens discussed here due to reworking, though it is likely Oligocene in age (13). This specimen indicates an individual less than 2/3rds the size of P. sandersi, which suggests conspecificity is unlikely. Meaningful comparisons are otherwise precluded by the fragmentary state of the material.
In comparison to other species of Pelagornis from outside the Atlantic coast of
North America, P sandersi can be distinguished from the Miocene Pelagornis miocaenus of Europe (known only from a humerus; note that this is a separate species from
Pelagornis mioceanus) and the Pliocene Pelagornis (=Osteodontornis) stirtoni of New Zealand by a >50% size difference, and additionally differs from P. stirtoni in markedly more robust femur. In P. stirtoni, the mandible is described as having an intraramal suture (18), whereas the caudal and rostral portions were connected only by a thin splint of bone in P. sandersi (see 19). Aside from size (>15% larger), P. sandersi differs from
Pelagornis mauretanicus from the Pliocene of Morocco in the different pattern of pseudotooth emplacement in the caudal part of the mandibular tooth row (the only directly comparable section). Previous anatomical studies (20) classified pseudoteeth into four easily distinguished types: rank 1 (very large), rank 2 (medium), rank 3 (small), and rank 4 (very thin and spine-like). The caudalmost rank 1 pseudotooth is separated from the next rank 1 pseudotooth by a sequence of a rank 3 pseudotooth, a rank 2 pseudotooth and a rank 3 pseudotooth in P. sandersi. In P. mauretanicus, the pattern in this portion of the jaw is instead rank 2, rank 4, rank 3, rank 4, rank 1. Although it is uncertain how much intraspecific variation exists in pseudotooth pattern, the large amount of temporal
(~20Ma) and geographical disparity also suggest these fossils do not belong to the same species. P. sandersi differs from the Miocene Pelagornis (=Osteodontornis) orri of
California in exhibiting two small pseudoteeth between the first two large pseudoteeth in the rostral portion of the upper jaw, whereas in P. orri there are six small intervening pseudoteeth. Cyphornis magnus is known only from a poorly preserved proximal portion of a tarsometatarsus of uncertain age from western Canada. While this fragmentary holotype of C. magnus cannot be adequately compared to P. chilensis, it is unlikely they belong to the same species based on the smaller size of the former (~15%) and the wide geographic separation. Finally, as has generally been noted by previous authors (e.g., 11-12,21),
Pelagornis can easily be differentiated from Eocene pelagornithids by a suite of features that are preserved in P. sandersi including straight pseudoteeth (rostrally slanted in
Lutetodontopteryx tethyensis, Caspiodontornis kobystanicus, and apparently in Dasornis toliapica, though see [12] regarding possible distortion), presence of the transverse furrow near the tip of the rostrum (versus absence in Dasornis toliapicus, Dasornis emuinus, and Lutetodontopteryx tethyensis), weak proximal projection of the caput humeri (stronger in specimens assigned to “Macrodontopteryx” oweni), the narrow ventral portion of the proximal end of the humerus, strongly projected tuberculum dorsale
(not seen in Dasornis emuinus) and absence of the distinct crest on the caudomedial section of the femoral shaft just proximal of the condylus medialis (versus presence in
Lutetodontopteryx tethyensis).
Table S1: Alternate estimates of primary feather length in P. sandersi.
Method Estimate (mm)
Isometric scaling of P. orri fossil feather. 550-630
Allometric scaling equation (22) treating species as independent data 441
0:78 points: Lprim = ta
0:79 Allometric scaling equation (22), using phylogeny (23): Lprim = ta 478
0:82 Allometric scaling equation (22), using phylogeny (24): Lprim = ta 603
Isometric scaling using skeleton: feather proportions in spread wing 1083 of Macronectes giganteus (USNM 631190) Table S2. Estimated Gliding Flight Parameters for Pelagornis sandersi
Input Values Results mass aspect ratio wingspan best glide ratio min. sink rate V (min. sink) V (best glide)
21.9kg 13 6.06m 21.6 0.477m/s 8.3m/s 12.7m/s
21.9kg 14 6.06m 22.5 0.466m/s 8.7m/s 12.9m/s
21.9kg 15 6.06m 23.3 0.457m/s 8.9m/s 13.0m/s
21.9kg 13 6.13m 21.7 0.471m/s 8.2m/s 12.6m/s
21.9kg 14 6.13m 22.5 0.461m/s 8.5m/s 12.8m/s
21.9kg 15 6.13m 23.3 0.451m/s 8.8m/s 12.9m/s
21.9kg 13 6.4m 21.8 0.451m/s 7.9m/s 12.1m/s
21.9kg 14 6.4m 22.6 0.440m/s 8.2m/s 12.3m/s
21.9kg 15 6.4m 23.5 0.431m/s 8.5m/s 12.4m/s
21.9kg 13 7.38m 22.1 0.389m/s 6.9m/s 10.6m/s
21.9kg 14 7.38m 23.0 0.380m/s 7.1m/s 10.8m/s 21.9kg 15 7.38m 23.9 0.372m/s 7.4m/s 10.9m/s
40.1kg 13 6.06m 21.0 0.653m/s 11.3m/s 16.8m/s
40.1kg 14 6.06m 21.8 0.639m/s 11.7m/s 17.0m/s
40.1kg 15 6.06m 22.5 0.627m/s 12.1m/s 17.2m/s
40.1kg 13 6.13m 21.0 0.645m/s 11.1m/s 16.6m/s
40.1kg 14 6.13m 21.8 0.631m/s 11.5m/s 16.8m/s
40.1kg 15 6.13m 22.6 0.619m/s 11.9m/s 17.0m/s
40.1kg 13 6.4m 21.2 0.616m/s 10.7m/s 16.0m/s
40.1kg 14 6.4m 22.0 0.603m/s 11.1m/s 16.2m/s
40.1kg 15 6.4m 22.8 0.591m/s 11.4m/s 16.4m/s
40.1kg 13 7.38m 21.6 0.530m/s 9.3m/s 14.1m/s
40.1kg 14 7.38m 22.5 0.518m/s 9.6m/s 14.3m/s
40.1kg 15 7.38m 23.3 0.508m/s 9.9m/s 14.5m/s
Figure S2. Glide polars for Pelagornis sandersi using values calculated in Flight 1.25 (25) from a series of analyses using 21.9kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades.
Figure S3: Glide polars for Pelagornis sandersi using values calculated in Flight 1.25 (25) from a series of analyses using 40.1kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades.
Figure S4: Lift/drag ratios for Pelagornis sandersi plotted against flight speed using values calculated in Flight 1.25 (25) from a series of analyses using 21.9kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades.
Figure S5: Lift/drag ratios for Pelagornis sandersi plotted against flight speed using values calculated in Flight 1.25 (25) from a series of analyses using 40.1kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades.
Table S3: Estimated Power Parameters for Pelagornis sandersi
Input Values Results mass aspect ratio wingspan maximum mechanical power minimum mechanical power
available from flight muscles required for horizontal flight
21.9kg 13 6.06m 78W 85.9W
21.9kg 14 6.06m 78W! 83.5W
21.9kg 15 6.06m 78W! 81.4W
21.9kg 13 6.13m 78W! 84.4W
21.9kg 14 6.13m 78W! 82.0W
21.9kg 15 6.13m 78W! 80.0W
21.9kg 13 6.4m 78W! 79.1W
21.9kg 14 6.4m 78W! 76.9W
21.9kg 15 6.4m 78W! 75.0W
21.9kg 13 7.38m 78W! 63.9W 21.9kg 14 7.38m 78W! 62.1W
21.9kg 15 7.38m 78W! 60.5W
40.1kg 13 6.06m 78W! 235W
40.1kg 14 6.06m 78W! 229W
40.1kg 15 6.06m 78W! 223W
40.1kg 13 6.13m 78W! 231W
40.1kg 14 6.13m 78W! 225W
40.1kg 15 6.13m 78W! 213W
40.1kg 13 6.4m 78W! 217W
40.1kg 14 6.4m 78W! 211W
40.1kg 15 6.4m 78W! 205W
40.1kg 13 7.38m 78W! 218W
40.1kg 14 7.38m 78W! 212W
40.1kg 15 7.38m 78W! 206W
Figure S6: Power curves for Pelagornis sandersi calculated in Flight 1.25 (25) from a series of analyses using 21.9kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades.
Figure S7: Power curves for Pelagornis sandersi calculated in Flight 1.25 (25) from a series of analyses using 40.1kg mass estimate and (a) 6.06m, (b) 6.13m, (c) 6.4m, and (d) 7.38m wingspan estimates. In each graph, runs using aspect ratio estimates of 13, 14, and 15 are shown in different shades. Supporting References
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