Comparative material utilized in Figures 3 and 6. Other specimens used for comparisons are referenced in-text, either via their catalog numbers (if they were studied directly) or by citations of source works with relevant figure/table numbers.

1. Tarsometatarsi used in Figure 3. Data for fossil specimens from IB/P/B and MLP after Myrcha et al. (2002, table 1), CM - after Slack et al. (2006) and Mayr et al. (2017a), MUSM - after Clarke et al. (2010), OU - after Marples (1952) and Ksepka et al. (2012); Trochlear widths for Inkayacu, Kairuku, Muriwaimanu, Waimanu, and CM 2016.158.1 as well as midwidths of Muriwaimanu, Waimanu and CM 2016.158.1 were assessed based on published photographs (with scales). Other measurements were taken directly by PJ.

a. Fossil bones

Anthropornis grandis
IB/P/B-0483, MLP 95-I-10-142, MLP 94-III-15-178

Anthropornis nordenskjoeldi

Archaeospheniscus lopdelli
NHMUK A4080 (cast)

Archaeospheniscus wimani
MLP 90-I-20-24, NHMUK A3331

Delphinornis arctowskii
IB/P/B-0484, MLP 93.X.1.92

Delphinornis gracilis

Delphinornis larseni
NRM-PZ A.21, NRM-PZ A.587, NRM-PZ A.861, NRM-PZ A.895, IB/P/B-0062, IB/P/B-0547, IB/P/B-0548, MLP 84.II.1.79, MLP 91.II.4.174, MLP 83.V.20.5

Inkayacu paracasensis
MUSM 1444

Kairuku grebneffi
OU 22094

Kairuku waitaki
OU 12652

Korora oliveri
OU C.50.63

Marambiornis exilis
IB/P/B-0490, MLP 93.X.1.111

Mesetaornis polaris

Muriwaimanu tuatahi
CM zfa 34

Palaeeudyptes antarcticus

Palaeeudyptes gunnari
IB/P/B-0072, IB/P/B-0277, IB/P/B-0487, MLP 91-II-4-222, MLP 87-II-1-45, MLP 82-IV-23-6, MLP 84-II-1-124’

Palaeeudyptes klekowskii
IB/P/B-0485, IB/P/B-0545, IB/P/B-0546, MLP 93-X-1-142, MLP 84-II-1-78, MLP 93-X-1-63, MLP 84-II-1-76, MLP 93-X-1-106, MLP 94-III-15-20, MLP 83-V-30-15, MLP 83-V-30-16, MLP 84-II-1-124

Palaeeudyptes marplesi
NHMUK A6119 (cast)

Waimanu manneringi
CM zfa 35

Undetermined Paleocene penguin from New Zealand
CM 2016.158.1

b. Modern bones

Aptenodytes forsteri
NHMUK/T 1197A, NHMUK/T 1197D, NHMUK/T 1197B, NHMUK/T 1972.1.25, NHMUK/T 1905.12.30.419, NHMUK/T 1998.55.2

Aptenodytes patagonicus
NHMUK/T 1846.4.15.33, NHMUK/T 701A, NHMUK/T 701B, NHMUK/T 1952.1.28, NHMUK/T 1972.1.24, NHMUK/T 2000.12.1

Eudyptes chrysocome
NHMUK/T 1952.1.39, NHMUK/T 1898.7.1.15, NHMUK/T 1964.14.2, NHMUK/T 1898.7.1.14

Eudyptula minor
NHMUK/T 1966.51.1, NHMUK/T 2002.2.1, NHMUK/T 1896.2.16.38

Pygoscelis adeliae
NHMUK/T 1849.10.2.2, NHMUK/T 1850.9.7.1, IB/P/B - three unnumbered specimens.

Pygoscelis papua
NHMUK/T 2006.1.16, IB/P/B - an unnumbered specimen,

Spheniscus demersus
NHMUK/T 1898.7.1.8, NHMUK/T 1898.7.1.9, NHMUK/T 1998.23.2, NHMUK/T 1998.48.24

2. Hip bones specimens used in Figure 6. Outlines of foramina for Kairuku grebneffi and Waimanu manneringi were assessed based on Ksepka et al. (2012, figure 6) and Slack et al. (2006, figure 1) respectively.

a. Fossil

Kairuku grebneffi
OU 22094

Waimanu manneringi
CM zfa 35

b. Modern

Aptenodytes forsteri
NHMUK/T 1972.1.25

Aptenodytes patagonicus
NHMUK/T 1846.4.15.32

Eudyptes chrysocome
NHMUK/T 1956.14.1

Eudyptula minor
NHMUK/T 2002.2.1

Pygoscelis adeliae
IB/P/B - an unnumbered specimen

Pygoscelis papua
IB/P/B - an unnumbered specimen

Spheniscus demersus
NHMUK/T 1905.5.23.1

Spheniscus humboldti
NHMUK/T 1952.1.42



Details of the shape-analysis workflow.






Harmonic coefficients (normalized) calculated for outlines of major hip bone foramina (nine outlines ˣ 16 harmonics, four coefficients for each harmonic).

appendix3 1

appendix3 2






Scatterplots of scores from the Principal Component Analysis (PCA) on harmonic coefficients calculated for outlines of major hip bone foramina (source data in Appendix 3).



Left hip bone of an extant penguin Eudyptula minor (NHMUK/T 1881.1.17.105) showing the ilioischiadic membrane (lateral view). Abbreviations: at, antitrochanter; iif, ilioischiadic foramen; iim, ilioischiadic membrane; il, ilium; is, ischium; pb, pubis; pdp, correlate of proximal dorsal process; pfe, proximal femur (broken). Scale bar equals 1 cm.