General aspects: A C4 in left lateral view, Aptenodytes forsteri (MLP-ORN 15192); B C8 in cranial view, Aptenodytes forsteri (MLP-ORN 15192); C C11 in left lateral view, Aptenodytes forsteri (MLP-ORN 15192); D C1–C13 in dorsal view, Pygoscelis papua (MLP-ORN 783); E CT1 in left lateral view, Aptenodytes forsteri (MLP-ORN 15192); F CT1 in cranial view, Pygoscelis adeliae (MLP-ORN 1134); G CT2 in cranial view, Pygoscelis adeliae (MLP-ORN 1134); H CT1 in cranial view, Spheniscus magellanicus (MLP-ORN 1598); I CT2 in cranial view, Spheniscus magellanicus (MLP-ORN 1598); J T1–T6 and synsacrum in left lateral view, Eudyptes chrysocome (MLP-ORN 1596); K T2 in cranial view, Aptenodytes forsteri (MLP-ORN 15192); L T6, T7 and the cranial end of the synsacrum in left lateral view, Pygoscelis adeliae (MACN-Or 68557); M T1–T7 in left lateral view, Spheniscus magellanicus (MACN-Or 71167); N T7 in left lateral view, Aptenodytes forsteri (MLP-ORN 15192); O T7 in cranial view, Spheniscus magellanicus (MACN-Or 71167); P Ca1–Ca7 in cranial view, Eudyptes chrysocome (MLP-ORN 1596); Q Ca1–Ca6 and pygostyle in left lateral view, Pygoscelis antarcticus (MLP-ORN 1138). R pygostyle in left lateral view, Eudyptes chrysocome (MLP-ORN 1596), adult; S pygostyle in left lateral view, Spheniscus magellanicus (MACN-Or 71167), juvenile, where the first vertebra is still unfused. Abbreviations: api – ala praeacetabularis ilii; av – arcus vertebrae; cv – corpus vertebrae; ec – eminentia costolateralis; fa – facies articularis; pc – processus costalis; pca – processus caroticus; ph – processus haemalis; ps – processus spinosus; pt – processus transversus; pvc – processus ventralis corporis. Scale bar: 10 mm.